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Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
SuWa 245
River productivity study (Study 9.8), 2013 initial river productivity results,
technical memorandum
Author(s) – Personal:
Author(s) – Corporate:
R2 Resource Consultants, Inc. and Alaska Cooperative Fish and Wildlife Research Unit, University
of Alaska Fairbanks
AEA-identified category, if specified:
September 26, 2014 technical memorandum filings
AEA-identified series, if specified:
Series (ARLIS-assigned report number): Existing numbers on document:
Susitna-Watana Hydroelectric Project document number 245
Published by: Date published:
[Anchorage, Alaska : Alaska Energy Authority, 2014] September 2014
Published for: Date or date range of report: Alaska Energy Authority
Volume and/or Part numbers:
Final or Draft status, as indicated:
Attachment F
Document type: Pagination:
Technical memorandum x, 86, 55 p.
Related work(s): Pages added/changed by ARLIS:
Cover letter to this report: Susitna-Watana Hydroelectric
Project, FERC Project no. 14241-000; Second set of 2014
technical memoranda for Initial Study Plan meetings. (SuWa
239)
Attachments A-E (SuWa 240-244) and G (SuWa 246)
Added cover letter
Notes:
All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS-
produced cover page and an ARLIS-assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna-watana/
September 26, 2014
Ms. Kimberly D. Bose
Secretary
Federal Energy Regulatory Commission
888 First Street, N.E.
Washington, D.C. 20426
Re: Susitna-Watana Hydroelectric Project, Project No. 14241-000
Second Set of 2014 Technical Memoranda for Initial Study Plan Meetings
Dear Secretary Bose:
As the Alaska Energy Authority (AEA) explained in its September 17, 2014 filing
with the Federal Energy Regulatory Commission (Commission or FERC) for the
proposed Susitna-Watana Hydroelectric Project, FERC Project No. 14241 (Project), the
June 3, 2014 Initial Study Report (ISR) provided for AEA to prepare certain technical
memoranda and other information based on 2014 work. In accordance with Commission
Staff direction, on September 17, 2014, AEA filed and distributed the first set of
technical memoranda and other information generated during the 2014 study season.
With this letter, AEA is filing and distributing the second set of technical
memoranda generated during the 2014 study season, as described below. As part of its
continued implementation of the study plan, AEA expects to file a third set of technical
memoranda prior to October 1, 2014.
This second set of technical memoranda includes:
• Attachment A: Geomorphology Study (Study 6.5) - Updated Mapping of
Aquatic Macrohabitat Types in the Middle Susitna River Segment from 1980s
and Current Aerials Technical Memorandum. This technical memorandum
updates the Middle Susitna River Segment portion of the aquatic macrohabitat
mapping results previously provided in the technical memorandum titled
Mapping of Aquatic Macrohabitat Types at Selected Sites in the Middle and
Lower Susitna River Segments from 1980s and 2012 Aerials (Tetra Tech
2013a).
• Attachment B: Geomorphology Study (Study 6.5) - Mapping of Geomorphic
Features and Turnover within the Middle and Lower Susitna River Segments
from 1950s, 1980s, and Current Aerials Technical Memorandum. This
technical memorandum updates the geomorphic mapping and assessment of
channel change that were initially provided in Mapping of Geomorphic
2
Features and Assessment of Channel Change in the Middle and Lower Susitna
River Segments from 1980s and 2012 Aerials (Tetra Tech 2013a). The initial
technical memorandum provided the results from tasks identified in Revised
Study Plan Study 6.5 Section 6.5.4.4. This update extends the previous 30
year analysis between the 1980s and 2012 by an additional 30 years with
aerial photography from the 1950s, and also provides a short term analysis of
geomorphic changes by comparing 2012 with 2013 aerial photography.
• Attachment C: Fluvial Geomorphology Modeling below Watana Dam Study
(Study 6.6) - Decision Point on Fluvial Geomorphology Modeling of the
Susitna River below PRM 29.9 Technical Memorandum. This technical
memorandum describes the decision of whether to extend the downstream
limit of the 1-D bed evolution model below Susitna Station at PRM 29.9.
• Attachment D: Fluvial Geomorphology Modeling Below Watana Dam (Study
6.6) - Winter Sampling of Main Channel Bed Material Technical
Memorandum. The overall purpose of this technical memorandum is to
quantify main channel bed material gradations at selected sites in the Upper,
Middle, and Lower Susitna River Segments. The data obtained from this
study serves as input for the 1-D and 2-D bed evolution modeling efforts
being conducted under the Fluvial Geomorphology Modeling Study (Study
6.6).
• Attachment E: Cook Inlet Beluga Whale Study (Study 9.17) - 2014 Cook Inlet
Beluga Whale Prey Study Implementation Technical Memorandum. This
technical memorandum summarizes activities implementing the Cook Inlet
Beluga Whale Study (Study 9.17) conducted in 2014 that tested methods to
document Cook Inlet Beluga Whale prey and prey habitat in the Susitna River
delta.
• Attachment F: River Productivity Study (Study 9.8) - 2013 Initial River
Productivity Results Technical Memorandum. This technical memorandum
provides a preliminary review and summary of 2013 river productivity sample
results based on laboratory data received after the ISR submittal in June 2014.
• Attachment G: River Productivity Study (Study 9.8) - 2014 Field Season River
Productivity Progress Report Technical Memorandum. This technical
memorandum presents an update on activities conducted during the Spring
field sampling event in June 2014, which was focused on data collection to
support the needs of the trophic modeling and stable isotope analysis
objectives of the River Productivity Study.
3
AEA appreciates the opportunity to provide this additional information to the
Commission and licensing participants, which it believes will be helpful in determining
the appropriate development of the 2015 study plan as set forth in the ISR. If you have
questions concerning this submission please contact me at wdyok@aidea.org or (907)
771-3955.
Sincerely,
Wayne Dyok
Project Manager
Alaska Energy Authority
Attachments
cc: Distribution List (w/o Attachments)
Attachment F
River Productivity Study (Study 9.8) - 2013 Initial River Productivity Results
Technical Memorandum
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
River Productivity Study
(Study 9.8)
2013 Initial River Productivity Results
Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
R2 Resource Consultants, Inc.
Alaska Cooperative Fish and Wildlife Research Unit,
University of Alaska Fairbanks
September 2014
TECHNICAL MEMORANDUM 2013 INITIAL RIVER PRODUCTIVITY RESULTS
TABLE OF CONTENTS
1. Introduction ........................................................................................................................1
2. Methods ...............................................................................................................................2
2.1. Characterization of benthic macroinvertebrate and algal communities .............2
2.1.1. Abundance Measures ...................................................................... 3
2.1.2. Richness Measures .......................................................................... 3
2.1.3. Composition Measures.................................................................... 4
2.1.4. Functional Feeding Groups ............................................................. 4
2.2. Benthic Macroinvertebrate Drift Estimation .....................................................4
2.3. Feasibility Study of the Talkeetna River as a reference ....................................4
2.4. Trophic analysis, using trophic modeling and stable isotope analysis, to
describe the food web relationships ...................................................................5
2.4.1. Trophic model development ........................................................... 5
2.4.2. Conduct stable isotope analysis of food web components to help
determine energy sources and pathways in the riverine
communities .................................................................................... 6
2.5. Characterize the invertebrate compositions in the diets of representative fish
species in relationship to their source (benthic or drift component) ..................7
2.6. Estimate benthic macroinvertebrate colonization rates in the Middle Susitna
River Segment under pre-Project baseline conditions to assist in evaluating
future post-Project changes to productivity in the Middle Susitna River. .........8
3. Results .................................................................................................................................8
3.1. Characterize the pre-Project benthic macroinvertebrate and algal communities
with regard to species composition and abundance in the Middle and Lower
Susitna River ......................................................................................................8
3.1.1. RP-184 (Watana Dam) .................................................................... 9
3.1.2. RP-173 (Stephan Lake Complex) ................................................. 10
3.1.3. RP-141 (Indian River)................................................................... 10
3.1.4. RP-104 (Whiskers Slough) ........................................................... 10
3.1.5. RP-81 (Montana Creek) ................................................................ 11
3.2. Estimate drift of benthic macroinvertebrates in selected habitats within the
Middle and Lower Susitna River to assess food availability to juvenile and
resident fishes...................................................................................................11
3.2.1. RP-184 (Watana Dam) .................................................................. 12
3.2.2. RP-173 (Stephan Lake Complex) ................................................. 13
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i September 2014
TECHNICAL MEMORANDUM 2013 INITIAL RIVER PRODUCTIVITY RESULTS
3.2.3. RP-141 (Indian River)................................................................... 13
3.2.4. RP-104 (Whiskers Slough) ........................................................... 13
3.2.5. RP-81 (Montana Creek) ................................................................ 14
3.3. Conduct a feasibility study in 2013 to evaluate the suitability of using
reference sites on the Talkeetna River to monitor long-term Project-related
change in benthic productivity. ........................................................................15
3.4. Conduct a trophic analysis, using trophic modeling and stable isotope
analysis, to describe the food web relationships in the current riverine
community within the Middle and Lower Susitna River .................................16
3.4.1. Develop a trophic model to estimate how environmental factors
and food availability affect the growth rate potential of focal fish
species under current and future conditions .................................. 16
3.4.2. Conduct stable isotope analysis of food web components to help
determine energy sources and pathways in the riverine
communities .................................................................................. 18
3.5. Characterize the invertebrate compositions in the diets of representative fish
species in relationship to their source (benthic or drift component) ................20
3.6. Estimate benthic macroinvertebrate colonization rates in the Middle Susitna
River Segment under pre-Project baseline conditions to assist in evaluating
future post-Project changes to productivity in the Middle Susitna River. .......21
4. Discussion..........................................................................................................................22
4.1. Benthic Macroinvertebrate and Algal Communities .......................................22
4.2. Drift of Benthic Macroinvertebrates ................................................................22
4.3. Feasibility of Talkeetna as a Reference ...........................................................23
4.4. Trophic Analysis of Food Web ........................................................................23
4.4.1. Trophic Model .............................................................................. 23
4.4.2. Stable isotope analysis of food web components ......................... 24
4.5. Invertebrate composition in the diets of representative fish species................25
4.6. Benthic Macroinvertebrate Colonization Rates ...............................................26
5. References .........................................................................................................................28
6. Tables ................................................................................................................................31
7. Figures ...............................................................................................................................45
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii September 2014
TECHNICAL MEMORANDUM 2013 INITIAL RIVER PRODUCTIVITY RESULTS
LIST OF TABLES
Table 3.1-1. Benthic macroinvertebrate sample totals for 2013 sampling during three index
events (Spr= Spring, Sum=Summer, Fall) and Post-Storm sampling for sites in the Middle
and Lower River Segments of the Susitna River for the River Productivity Study.............. 32
Table 3.1-2. Summary benthic metrics for sites at River Productivity stations in Middle Reach
above Devils Canyon. ........................................................................................................... 33
Table 3.1-3. Summary benthic metrics for sites at River Productivity stations in Middle Reach
below Devils Canyon. ........................................................................................................... 34
Table 3.1-4. Summary benthic metrics for sites at River Productivity stations in Lower Reach
downstream of the confluence with Chulitna River.............................................................. 35
Table 3.2-1. Benthic drift and plankton tow sample totals for 2013 sampling during three index
events (Spr= Spring, Sum=Summer, Fall) and Post-Storm for sampling sites in the Middle
and Lower River Segments of the Susitna River for the River Productivity Study.............. 36
Table 3.2-2. Summary drift and plankton metrics for sites at River Productivity stations in
Middle Reach above Devils Canyon. .................................................................................... 37
Table 3.2-3. Summary drift and plankton metrics for sites at River Productivity stations in
Middle Reach below Devils Canyon. ................................................................................... 38
Table 3.2-4. Summary drift and plankton metrics for sites at River Productivity stations in
Lower Reach downstream of confluence with Chulitna River. ............................................ 39
Table 3.3-1. Benthic macroinvertebrate sample totals for 2013 sampling during three index
events (Spring, Summer, Fall) for sites in the Talkeetna River (TKA) for the River
Productivity Study. ............................................................................................................... 40
Table 3.3-2. Benthic drift and plankton tow sample totals for 2013 sampling during three index
events (Spring, Summer, Fall) for sites in the Talkeetna (TKA) River for the River
Productivity Study. ............................................................................................................... 40
Table 3.4-1. Bioenergetics model results showing the growth, consumption rate, and growth
efficiency of juvenile Chinook and coho salmon. Growth and consumption were simulated
for 91-day intervals between the spring and fall sampling events (Spr-Fall) or for 31-day
intervals between the summer and fall events (Sum-Fall), depending on the availability of
input data. .............................................................................................................................. 41
Table 3.4-2. Total consumption by juvenile Chinook and coho salmon broken down by
individual prey categories, as estimated by bioenergetics models. Prey categories included
fish eggs, fish, aquatic invertebrates, terrestrial insects (aquatic origin), and terrestrial
insects (terrestrial origin). ..................................................................................................... 42
Table 3.4-3. Total stable isotope samples analyzed in 2013. ....................................................... 43
Table 3.5-1. MANCOVA models testing for temporal, spatial, and ontogenetic differences in
diet composition of juvenile Chinook salmon and juvenile coho salmon. Degrees of
freedom (df) are listed for both hypothesis and error terms. ................................................ 44
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii September 2014
TECHNICAL MEMORANDUM 2013 INITIAL RIVER PRODUCTIVITY RESULTS
LIST OF FIGURES
Figure 2.1-1. Middle Susitna River Segment, with the four River Productivity sampling stations
/Instream Flow Focus Areas selected for the River Productivity Study, plus the sampling
station for reference sites on the Talkeetna River. ................................................................ 46
Figure 2.1-2. Lower Susitna River Segment, with Montana Creek area River Productivity
sampling station selected for the River Productivity Study. ................................................. 47
Figure 3.1-1. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected
in 2013 during three index events for sites within the Watana Dam Focus Area (FA-173) in
the Middle River Segment of the Susitna River for the River Productivity Study. .............. 48
Figure 3.1-2. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples
collected in 2013 during three index events for sites within the Watana Dam Focus Area
(FA-184) in the Middle River Segment of the Susitna River for the River Productivity
Study. .................................................................................................................................... 48
Figure 3.1-3. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5)
from Hess and petite Ponar grab samples collected in 2013 during three index events for
sites within the Watana Dam Focus Area (FA-184) in the Middle River Segment of the
Susitna River for the River Productivity Study. ................................................................... 49
Figure 3.1-4. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected
in 2013 during three index events for sites within the Stephan Lake Complex Focus Area
(FA-173) in the Middle River Segment of the Susitna River for the River Productivity
Study. .................................................................................................................................... 49
Figure 3.1-5. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples
collected in 2013 during three index events for sites within the Stephan Lake Complex
Focus Area (FA-173) in the Middle River Segment of the Susitna River for the River
Productivity Study. ............................................................................................................... 50
Figure 3.1-6. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5)
from Hess and petite Ponar grab samples collected in 2013 during three index events for
sites within the Stephan Lake Complex Focus Area (FA-173) in the Middle River Segment
of the Susitna River for the River Productivity Study. ......................................................... 50
Figure 3.1-7. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected
in 2013 during three index events for sites within the Indian River Focus Area (FA-141) in
the Middle River Segment of the Susitna River for the River Productivity Study. .............. 51
Figure 3.1-8. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples
collected in 2013 during three index events for sites within the Indian River Focus Area
(FA-141) in the Middle River Segment of the Susitna River for the River Productivity
Study. .................................................................................................................................... 51
Figure 3.1-9. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5)
from Hess and petite Ponar grab samples collected in 2013 during three index events for
sites within the Indian River Focus Area (FA-141) in the Middle River Segment of the
Susitna River for the River Productivity Study. ................................................................... 52
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv September 2014
TECHNICAL MEMORANDUM 2013 INITIAL RIVER PRODUCTIVITY RESULTS
Figure 3.1-10. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected
in 2013 during three index events for sites within the Whiskers Slough Focus Area (FA-
104) in the Middle River Segment of the Susitna River for the River Productivity Study. . 52
Figure 3.1-11. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples
collected in 2013 during three index events for sites within the Whiskers Slough Focus Area
(FA-104) in the Middle River Segment of the Susitna River for the River Productivity
Study. .................................................................................................................................... 53
Figure 3.1-12. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates
(n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events
for sites within the Whiskers Slough Focus Area (FA-104) in the Middle River Segment of
the Susitna River for the River Productivity Study. ............................................................. 53
Figure 3.1-13. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected
in 2013 during three index events for sites within the Montana Creek area (RP-81) in the
Lower River Segment of the Susitna River for the River Productivity Study. ..................... 54
Figure 3.1-14. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples
collected in 2013 during three index events for sites within the Montana Creek area (RP-81)
in the Lower River Segment of the Susitna River for the River Productivity Study. ........... 54
Figure 3.1-15. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates
(n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events
for sites within the Montana Creek area (RP-81) in the Lower River Segment of the Susitna
River for the River Productivity Study. ................................................................................ 55
Figure 3.2-1. Mean drift density estimates from drift samples (n=2) collected in 2013 during
three index events for sites within the Watana Dam Focus Area (FA-184) in the Middle
River Segment of the Susitna River for the River Productivity Study. ................................ 56
Figure 3.2-2. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5)
collected in 2013 during three index events for sites within the Stephan Lake Complex
Focus Area (FA-173) in the Middle River Segment of the Susitna River for the River
Productivity Study. ............................................................................................................... 56
Figure 3.2-3. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5)
collected in 2013 during three index events for sites within the Indian River Focus Area
(FA-141) in the Middle River Segment of the Susitna River for the River Productivity
Study. .................................................................................................................................... 57
Figure 3.2-4. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5)
collected in 2013 during three index events for sites within the Whiskers Slough Focus Area
(FA-104) in the Middle River Segment of the Susitna River for the River Productivity
Study. .................................................................................................................................... 57
Figure 3.2-5. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5)
collected in 2013 during three index events for sites within the Montana Creek area (RP-81)
in the Lower River Segment of the Susitna River for the River Productivity Study. ........... 58
Figure 3.3-1. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected
in 2013 during three index events for three sites on the Talkeetna River (TKA) for the River
Productivity Study. ............................................................................................................... 59
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v September 2014
TECHNICAL MEMORANDUM 2013 INITIAL RIVER PRODUCTIVITY RESULTS
Figure 3.3-2. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples
collected in 2013 during three index events for three sites on the Talkeetna River (TKA) for
the River Productivity Study. ................................................................................................ 59
Figure 3.3-3. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5)
from Hess and petite Ponar grab samples collected in 2013 during three index events for
three sites on the Talkeetna River (TKA) for the River Productivity Study......................... 60
Figure 3.3-4. Mean drift density estimates (individuals/ft3) from drift samples (n=2) and
plankton tows (n=5) collected in 2013 during three index events for three sites on the
Talkeetna River (TKA) for the River Productivity Study..................................................... 60
Figure 3.4-1. Monthly length-frequency distributions of juvenile Chinook salmon sampled in the
Middle and Lower Susitna River during 2013. Y-axes differ among plots.......................... 61
Figure 3.4-2. Monthly length-frequency distributions of juvenile coho salmon sampled in the
Middle and Lower Susitna River during 2013. Y-axes differ among plots.......................... 62
Figure 3.4-3. Box plots showing the length distribution of Chinook salmon as determined by the
scale analysis. No Chinook salmon smaller than 50 mm were aged, so the true length
distribution of age-0 fish extends to smaller sizes than indicated in the figure. Horizontal
lines indicate the median value of each group, rectangles indicate the 25th and 75th
percentiles, and whiskers and closed circles indicate values outside this range. .................. 63
Figure 3.4-4. Box plots showing the length distribution of coho salmon as determined by the
scale analysis. No coho salmon smaller than 48 mm were aged, so the true length
distribution of age-0 fish extends to smaller sizes than indicated in the figure. Horizontal
lines indicate the median value of each group, rectangles indicate the 25th and 75th
percentiles, and whiskers and closed circles indicate values outside this range. .................. 64
Figure 3.4-5. Monthly length-frequency distributions of juvenile Chinook salmon sampled at
station RP-104, Whiskers Creek and Slough, during 2013. Y-axes differ among plots. ..... 65
Figure 3.4-6. Monthly length-frequency distributions of juvenile Chinook salmon sampled at
station RP-141, Indian River, during 2013. Y-axes differ among plots. .............................. 66
Figure 3.4-7. Generalized growth trajectories for age-0, age-1, and age-2 Chinook salmon,
developed from empirical data for bioenergetics model inputs. Separate growth patterns
were developed using data from RP-104 (Whiskers Creek and Slough) and RP-141 (Indian
River). The growth rates reported in the Middle Susitna River during 1984 are shown for
comparison. ........................................................................................................................... 67
Figure 3.4-8. Monthly length-frequency distributions of juvenile coho salmon sampled at station
RP-104, Whiskers Creek and Slough, during 2013. Y-axes differ among plots. ................. 68
Figure 3.4-9. Monthly length-frequency distributions of juvenile coho salmon sampled at station
RP-141, Indian River, during 2013. Y-axes differ among plots. .......................................... 69
Figure 3.4-10. Generalized growth trajectories for age-0 and age-1 coho salmon, developed from
empirical data for bioenergetics model inputs. Separate growth patterns were developed
using data from RP-104 (Whiskers Creek and Slough) and RP-141 (Indian River). The
growth rates reported in the Middle Susitna River during 1984 are shown for comparison. 70
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TECHNICAL MEMORANDUM 2013 INITIAL RIVER PRODUCTIVITY RESULTS
Figure 3.4-11. Stable isotope δ13C values of all endmember samples collected in 2013 within
Focus Areas 81, 104, 141, and 184. ...................................................................................... 71
Figure 3.4-12. Stable isotope δ13C of all algae samples collected in 2013. Data points are
stratified by season, macrohabitat type, and Focus Area. ..................................................... 72
Figure 3.4-13. Stable isotope δ13C of all benthic organic matter samples collected in 2013. Data
points are stratified by season, macrohabitat type, and Focus Area. .................................... 73
Figure 3.4-14. Stable isotope δ13C of all organic matter drift samples collected in 2013. Data
points are stratified by season, macrohabitat type, and Focus Area. .................................... 74
Figure 3.4-15. Diet proportion estimates from stable isotope mixing model showing seasonal
trends in diet composition of juvenile Chinook salmon, juvenile coho salmon, and juvenile
and adult rainbow trout sampled between June and October................................................ 75
Figure 3.4-16. Diet proportion estimates from stable isotope mixing model showing trends
among study reaches in diet composition of juvenile Chinook salmon, juvenile coho
salmon, and juvenile and adult rainbow trout sampled between June and October. ............ 76
Figure 3.4-17. Diet proportion estimates from stable isotope mixing model showing trends
between macrohabitat types in diet composition of juvenile Chinook salmon, juvenile coho
salmon, and juvenile and adult rainbow trout sampled between June and October. ............ 77
Figure 3.5-1. Proportion (by dry mass) of fish eggs in the stomach contents of individual fish
sampled by gastric lavage, as a function of fork length. ....................................................... 78
Figure 3.5-2. Proportion (by dry mass) of prey fish in the stomach contents of individual fish
sampled by gastric lavage, as a function of fork length. ....................................................... 79
Figure 3.5-3. Seasonal trends in diet composition of juvenile Chinook salmon, juvenile coho
salmon, and juvenile and adult rainbow trout sampled between June and October in the
Susitna River. ........................................................................................................................ 80
Figure 3.5-4. Large-scale spatial trends in diet composition of juvenile Chinook salmon, juvenile
coho salmon, and juvenile and adult rainbow trout sampled at three focus areas Susitna
River. ..................................................................................................................................... 81
Figure 3.5-5. Small-scale spatial trends in diet composition of juvenile Chinook salmon, juvenile
coho salmon, and juvenile and adult rainbow trout sampled in four macrohabitat types in the
Susitna River. ........................................................................................................................ 82
Figure 3.6-1. Mean density estimates (n=3) from Hester-Dendy multiplate samplers collected in
clear and warm water conditions (HD-1) in the Whiskers Slough Focus Area (FA-104)
during August and September 2013 for an 8-week colonization period for the River
Productivity Study. ............................................................................................................... 83
Figure 3.6-2. Mean density estimates (n=3) from Hester-Dendy multiplate samplers collected in
clear and cold water conditions (HD-2) in the Whiskers Slough Focus Area (FA-104) during
August and September 2013 for an 8-week colonization period for the River Productivity
Study. .................................................................................................................................... 83
Figure 3.6-3. Mean taxa richness estimates (n=3) from Hester-Dendy multiplate samplers
collected in clear and warm water conditions (HD-1) in the Whiskers Slough Focus Area
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vii September 2014
TECHNICAL MEMORANDUM 2013 INITIAL RIVER PRODUCTIVITY RESULTS
(FA-104) during August and September 2013 for an 8-week colonization period for the
River Productivity Study. ...................................................................................................... 84
Figure 3.6-4. Mean taxa richness estimates (n=3) from Hester-Dendy multiplate samplers
collected in clear and cold water conditions (HD-2) in the Whiskers Slough Focus Area
(FA-104) during August and September 2013 for an 8-week colonization period for the
River Productivity Study. ...................................................................................................... 84
Figure 3.6-5. Mean density estimates (n=3) from Hester-Dendy multiplate samplers collected in
turbid and cold water conditions (HD-3) in the Whiskers Slough Focus Area (FA-104)
during August and September 2013 for an 8-week colonization period for the River
Productivity Study. ............................................................................................................... 85
Figure 3.6-6. Mean density estimates (n=3) from Hester-Dendy multiplate samplers collected in
turbid and warm water conditions (HD-4) in the Whiskers Slough Focus Area (FA-104)
during August and September 2013 for an 8-week colonization period for the River
Productivity Study. ............................................................................................................... 85
Figure 3.6-7. Mean taxa richness estimates (n=3) from Hester-Dendy multiplate samplers
collected in turbid and cold water conditions (HD-3) in the Whiskers Slough Focus Area
(FA-104) during August and September 2013 for an 8-week colonization period for the
River Productivity Study. ...................................................................................................... 86
Figure 3.6-8. Mean taxa richness estimates (n=3) from Hester-Dendy multiplate samplers
collected in turbid and warm water conditions (HD-4) in the Whiskers Slough Focus Area
(FA-104) during August and September 2013 for an 8-week colonization period for the
River Productivity Study. ...................................................................................................... 86
APPENDICES
Appendix A. Additional Tables and Figures
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LIST OF ACRONYMS AND SCIENTIFIC LABELS
Abbreviation Definition
δ13C Carbon-13 isotopic signature, reported in parts per thousand (per mil, ‰)
‰ parts per thousand (per mil
ADF&G Alaska Department of Fish and Game
AEA Alaska Energy Authority
ANOVA Analysis of Variance
BMI benthic macroinvertebrates
EPT Ephemeroptera, Plecoptera, and Trichoptera, insect orders of typically sensitive taxa
FA Focus Areas
FERC Federal Energy Regulatory Commission
FL Fork length
ft3 cubic foot (feet)
g gram
H’ Shannon-Wiener diversity index, calculated to represent diversity
HCl Hydrochloric acid
HD Hester-Dendy, multiplate sampler
HSC habitat suitability curve
ILP Integrated Licensing Process
IP Implementation Plan
ISR Initial Study Report
J joule
J’ Pielou’s J’, an index of community evenness
m2 square meter(s)
MANCOVA Multivariate analysis of covariance
MixSIAR A Bayesian stable isotope mixing model
mm millimeter(s)
NAWQA National Water-Quality Assessment
OM organic matter
P P-value or calculated probability. The estimated probability of rejecting the null
hypothesis (H0) of a study question when that hypothesis is true.
PIT-tag Passive Integrated Transponder tags used to individually identify animals and monitor
their movements.
QA/QC quality assurance/quality control
RP River Productivity
RSP Revised Study Plan
SIA stable isotope analysis
SPD Study Plan Determination
TKA Talkeetna River
UAF University of Alaska Fairbanks
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Abbreviation Definition
USEPA United States Environmental Protection Agency
USGS United States Geological Survey
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1. INTRODUCTION
Following the first study season in 2013, FERC’s regulations for the Integrated Licensing
Process (ILP) required AEA to “prepare and file with the Commission an initial study report
describing its overall progress in implementing the study plan and schedule and the data
collected, including an explanation of any variance from the study plan and schedule.” (18 CFR
5.15(c)(1)) The Initial Study Report (ISR) on River Productivity (RP) was prepared in
accordance with FERC’s ILP regulations and detailed AEA’s status in implementing the study,
as set forth in the FERC-approved Revised Study Plan (RSP), the Implementation Plan (IP), and
as modified by FERC’s April 1 SPD (collectively referred to herein as the “Study Plan”).
At the time of submission of the ISR, laboratory results of the samples collected during the 2013
field collection efforts were still pending. Thus, the purpose of this technical memorandum is to
provide a preliminary review and summary of 2013 results based on laboratory data received
after the ISR submittal in June 2014. While data analyses and data collection are still ongoing,
this technical memorandum provides preliminary results based on one year of study for five of
the eight study objectives to be completed. Those objectives are:
• Characterize the pre-Project benthic macroinvertebrate and algal communities with
regard to species composition and abundance in the Middle and Lower Susitna River.
• Estimate drift of benthic macroinvertebrates in selected habitats within the Middle and
Lower Susitna River to assess food availability to juvenile and resident fishes.
• Conduct a trophic analysis to describe the food web relationships within the current
riverine community within the Middle and Lower Susitna River.
• Characterize the invertebrate compositions in the diets of representative fish species in
relationship to their source (benthic or drift component).
• Estimate benthic macroinvertebrate colonization rates in the Middle Susitna Segment
under pre-Project baseline conditions to assist in evaluating future post-Project changes
to productivity in the Middle Susitna River.
Data analyses on the remaining study objectives are still in progress. These include:
• Conduct a feasibility study in 2013 to evaluate the suitability of using reference sites on
the Talkeetna River to monitor long-term Project-related change in benthic productivity.
• Develop habitat suitability criteria for Susitna benthic macroinvertebrate and algal
habitats to predict potential change in these habitats downstream of the proposed dam
site.
• Characterize organic matter resources (e.g., available for macroinvertebrate consumers)
including coarse particulate organic matter, fine particulate organic matter, and
suspended organic matter in the Middle and Lower Susitna River.
Preliminary results for the Talkeetna River sites are provided in this technical memorandum, but
more analysis is necessary to evaluate their comparability with study sites sampled on the
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Susitna River. This analysis, as well as results regarding the additional objectives above, will be
included in the USR. Development of the habitat suitability criteria (HSC) is dependent on
completion of metric calculations for benthic macroinvertebrates, algae, drift, and analyzing
those metrics with the environmental data that was collected in the field. The HSC analysis is in
progress and there are no results to report on at this time. Organic matter was analyzed by
utilizing the sorted debris from processed invertebrate samples. The laboratory analyses of these
fractions was conducted after the completion of the invertebrate sample processing. Final data
sets were delivered in July 2014, therefore data QA/QC and analysis is currently in progress at
this time.
2. METHODS
Field methods for all 2013 study activities were presented in the Initial Study Report (AEA 2014,
Study 9.8) and are not repeated in this technical memo. The methods presented below are
intended to supplement the methods presented in the ISR by describing the sample processing
and analytical methods applied to 2013 data collections. These supplemental methods are
presented below by study objective.
2.1. Characterization of benthic macroinvertebrate and algal
communities
Benthic macroinvertebrate sampling was conducted at five stations located in the Middle
Segment and upper portion of the Lower Segment on the Susitna River (Figures 2.1-1 and 2.1-2).
Benthic macroinvertebrate replicate samples were stored in individual containers and
immediately preserved in the field with 95 percent ethanol (non-denatured). Samples were
shipped to and processed by Ecoanalysts, Inc. (Moscow, Idaho) using sample processing
protocols established by the USEPA for the Rapid Bioassessment Protocols (Barbour et al. 1999)
and modified for use in Alaska (Major and Barbour 2001). Organic matter (OM) content from
processed subsampled material was retained and analyzed by size (coarse and fine particulate
OM).
The taxonomic composition of each sample was used to generate a taxa-abundance matrix. The
matrix was reviewed and adjusted for different levels of taxonomy. When identifying
macroinvertebrates, some specimens were either too immature or too damaged for identification
at the genus-level, and could only be assigned to a higher taxonomic level (e.g., family,
subfamily, order). For instance, a sample may contain individuals identifiable only to the mayfly
family Baetidae, yet also contain individuals clearly identified to one or more genera within this
family (e.g., Baetis tricaudatus, Diphetor hageni). This situation can lead to inflated estimates
of the number of taxa in a sample.
To prevent the inflation of metrics, the abundances of these “parent” taxa were distributed
proportionately among their composite taxa. This apportioning is similar to the method used by
the USGS NAWQA studies to correct for “ambiguous taxa” (Cuffney et al. 1997). The
abundances of “parent” taxa (orders, families) were retained in analysis when there were no
composite taxa identified in the sample.
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After applying the corrective measures used in preparing the taxa-abundance matrix, the data
were used to calculate a number of descriptive metrics commonly used in aquatic ecological
studies. These metrics were classified as abundance measures, richness measures, composition
measures, and functional feeding groups.
2.1.1. Abundance Measures
Macroinvertebrate abundance is represented by density, which is the total number of individuals
collected in a unit area. Subsample enumerations were expanded to provide a density estimate
(individuals/m²) for each sample.
2.1.2. Richness Measures
Metrics used to describe macroinvertebrate species richness include: taxa richness,
Ephemeroptera Plecoptera Trichoptera (EPT) richness, diversity, and evenness.
Taxa richness is the number of different types, or taxa, of invertebrates occurring in a given
ecosystem or sample. It is important to discern the two different taxa richness values generated
for this report:
The mean taxa richness is the average number of taxa collected from the four samples
collected at a site, not the site’s total taxa richness. By averaging the taxa richness of the
samples, the influence of rare taxa is minimized, thus reducing the taxa richness score.
The total taxa richness for a site is simply a tally of all taxa collected at a site, utilizing
all collected samples. Thus, the occurrence of rare taxa is given a weight equal to
common taxa. As a result, total taxa richness indicates larger estimates of taxa richness
than mean taxa richness. While total taxa richness may not lend itself to statistical
analysis in the short-term study, it provides a measure of contrast between sites, and may
become statistically useful in the long-term program.
EPT richness is the number of taxa from the insect orders of Ephemeroptera (mayflies),
Plecoptera (stoneflies), and Trichoptera (caddisflies). Following protocols from numerous state
and federal agencies, taxa richness values were calculated separately for each order. Both mean
and total EPT taxa richness values were determined.
Chironomid taxa richness is the number of taxa from the insect family Chironomidae (midges,
Order = Diptera). Because Chironomidae are typically dominant in Alaskan streams (Oswood
1989), identifications were made to genus level to fully reflect the taxonomic richness in the
Susitna River. This metric reflects the contribution of chironomids to the taxa richness measure.
Ecological diversity is a measure of community structure defined by the relationship between the
number of distinct taxa and their relative abundance. The Shannon-Wiener diversity index (H')
was calculated (log e) to represent diversity. This index usually lies between 1.5 and 3.5 for
ecological data. Higher index numbers indicate greater diversity, and the presence of a complex
ecological community. Diversity usually decreases with impaired habitat or water quality, or
increased disturbance. Pielou’s J’, an index of community evenness, was also calculated.
Values range from 0 to 1.0. Higher values indicate a more even spread in the community.
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2.1.3. Composition Measures
The relative abundance of major taxonomic groups provides information on a stream
community’s structure and the relative contribution of the populations to the total fauna (Barbour
et al. 1999). Eight major taxonomic groups were used to describe the community structure in our
analysis: Ephemeroptera, Plecoptera, Trichoptera, Coleoptera (beetles), Chironomidae (midges),
Diptera (true flies other than midges), Other Insects, and Non-insects. Composition measures of
certain taxonomic groups are often used as indicators of impairment in streams. For example, an
increase in the relative abundance of Chironomidae or non-insect taxa, or a decrease in the
relative abundance of Plecoptera or Trichoptera, may indicate environmental stress in a stream.
For plankton tow samples (Section 3 of this report), zooplankton were broken out from Non-
insects, due to their importance to those samples.
The EPT:Chironomid ratio is a ratio of the abundance of Ephemeroptera, Plecoptera,
Trichoptera in relation to chironomids. The ratio ranges from 0 to 1, with scores below 0.5
indicating more Chironomidae in the community.
The percent dominant taxa metric is the relative abundance of the most abundant taxa in a
sample: the most abundant taxon, and the top three most abundant taxa, were calculated.
Disturbances usually cause the abundance of a few taxa to increase and an elevation of the
percent dominance of the most abundant taxa.
2.1.4. Functional Feeding Groups
Benthic macroinvertebrate taxa abundances were allocated into functional-feeding group
categories according to their preferred methods of gathering food, based on determinations of the
primary feeding mechanism by Barbour et al. (1999). The major functional-feeding groups used
in our analysis were: collector-gatherers, collector-filterers, scrapers, shredders, predators, and
parasites as defined by Cummins et al. (2008). All other functional feeding groups, and any
individuals with unclassified or unknown feeding mechanisms, were consolidated into a seventh
group, “Others.” Data are presented as a percent of the total sample abundance.
2.2. Benthic Macroinvertebrate Drift Estimation
Invertebrate drift and plankton tow samples were shipped to and processed by Ecoanalysts, Inc.
(Moscow, Idaho) using methods similar to those used for benthic samples (Barbour et al. 1999;
Major and Barbour 2001). Organic matter (OM) content was retained and analyzed by size
(coarse and fine particulate OM). Data received was prepared for benthic macroinvertebrate
samples as detailed in Section 2.1. Density was measured by volume, per cubic foot, and all
metrics dependent upon density estimates reflect this as well.
2.3. Feasibility Study of the Talkeetna River as a reference
Benthic macroinvertebrate samples, invertebrate drift, and plankton tow samples were collected
during the same seasonal events as samples on the Susitna River, using the same field collection
methods. Samples were shipped to and processed by Ecoanalysts, Inc. (Moscow, Idaho) using
the same methods used for benthic and seston samples from the Susitna River samples collected
(Barbour et al. 1999; Major and Barbour 2001). Data received was prepared same as for benthic
macroinvertebrate and drift samples, as detailed in Sections 2.1 and 2.2.
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2.4. Trophic analysis, using trophic modeling and stable isotope
analysis, to describe the food web relationships
2.4.1. Trophic model development
In 2013, bioenergetics models were developed for each study site where adequate growth, diet
composition, and temperature data were collected. Growth inputs were compiled for two
sampling stations (RP-104 and RP-141; Figure 2.1-1) for Chinook and coho salmon (see Section
3. Results). Diet composition data was considered adequate if four or more fish of a given
species were sampled in at least two seasons, providing a starting and ending point for
simulations. Diet and temperature data were available for all three seasons at two sites for
Chinook salmon (RP-104 side slough and RP-141 tributary mouth) and one site for coho salmon
(RP-141 tributary mouth). In addition, diet data were available for two seasons at five additional
sites for coho salmon (RP-81 tributary mouth, spring and summer; RP-81 upland slough, spring
and fall; RP-104 side channel, summer and fall; RP-104 side slough, summer and fall; and RP-
104 upland slough, summer and fall). Adequate growth and temperature data were available for
the RP-104 side slough and upland slough sites, and these were modeled. Growth inputs were
not available for coho salmon at RP-81, and a full temperature time series was not available at
the RP-104 side channel, where the temperature logger appeared to be above water for nine days
of the 22-day interval when diet data was available. Therefore, these sites were excluded from
modeling. Too few rainbow trout were sampled during 2013 to adequately characterize the size-
at-age relationship from scales, so this species was not modeled.
Length distribution data were compiled from all fish captured in each study station by the River
Productivity and Fish Distribution and Abundance in the Middle and Lower River Studies.
Monthly length-frequency distributions were examined for Chinook salmon and coho salmon at
stations RP-104 and RP-141. Distinct size modes were provisionally identified as age-0, age-1,
or age-2 fish. All fish sampled in this study were aged, except for a small number for which all
scales were regenerated or otherwise unreadable. Ages were assigned based on the presence of
annuli and the number of circuli following the criteria of Moulton (1997). Scales were aged
independently by two readers with prior aging experience, and a third experienced reader acted
as a tie-breaker when necessary.
Modal fork lengths (FL, mm) were converted to wet weights (W, g) for input to the model using
length-weight relationships developed for juvenile Chinook salmon:
W = 1.13 x 10-5 FL2.98 (n = 2,014, r2 = 0.93), (1)
and for juvenile coho salmon:
W = 1.61 x 10-6 FL2.98 (n = 3,309, r2 = 0.89), (2)
in the Middle and Lower Susitna River based on the combined length and weight data collected
in 2013 by the River Productivity and Fish Distribution and Abundance in the Middle and Lower
River Studies.
For modeling purposes, all diet items were grouped into five categories: fish eggs, fish, aquatic
invertebrates, terrestrial invertebrates of aquatic origin (such as adult chironomid midges), and
terrestrial invertebrates of terrestrial origin (such as beetles). We estimated the energy density
(J/g wet weight) of prey items as 9,000 for salmon eggs, based on a review of measured values in
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the literature (Armstrong 2010), 5,200 for fish, based on the mean size of fish prey found in
stomach contents (39 mm FL, 0.6 g) and a size-based energy density relationship for sockeye
salmon (Beauchamp et al. 1989), and standard estimates for aquatic and terrestrial invertebrates
(3,967 and 3,600 respectively; Cummins and Wuycheck 1971). The diet analysis showed that
juvenile Chinook salmon and coho salmon ate large numbers of fish eggs after reaching 72 and
59 mm, respectively. Fish also comprised a large fraction of the diet of juvenile Chinook salmon
larger than 63 mm during spring. To incorporate these ontogenetic shifts into the simulations,
we excluded fish and fish eggs from the diet of salmon until they reached these threshold sizes,
and specified the diet composition of smaller fish based on only the invertebrate components of
the overall diet.
Using these input data, we estimated the consumption rate (g wet mass / day) of prey by juvenile
Chinook salmon and coho salmon during the interval between sampling dates with Wisconsin
bioenergetics models (Hanson et al. 1997). The models were implemented in the program R (R
Core Team 2014), using physiological parameters for Chinook salmon (Stewart and Ibarra 1991;
Madenjian et al. 2004) and coho salmon (Stewart and Ibarra 1991). The models iteratively
adjusted the ration size of simulated fish, expressed as a proportion P of the theoretical
maximum consumption rate (Cmax), until the simulated growth equaled the observed growth.
Lower values of P (near zero) indicated that growth was limited by low food intake, while higher
values closer to 1 indicated that feeding rates were high and growth was mostly limited by
thermal constraints on digestion and metabolism or by the quality of food. Growth efficiency (g
total growth / g total consumption) was computed for each simulation to indicate the percent of
energy intake that was allocated to growth as opposed to metabolism and waste. These metrics
were then compared among sampling sites to determine whether growth was limited primarily by
water temperature, food consumption, or food quality in the study area, and whether these
limiting factors differed among habitats (McCarthy et al. 2009).
In 2013, low catch related to access limitations and target species distributions resulted in
smaller than expected fish sample sizes. Consequetnly the data were not conducive for
parameterizing preliminary growth rate potential models and evaluation with a sensitivity
analysis as described in the Revised Study Plan. This study element will be completed after the
2014 field season when additional data samples will be collected. Access limitations have been
address for 2014 and target species adjustments have been made for sites upstream and
downstream of Devils Canyon to haelp ensure sufficient sample sizes will be collected in 2014.
2.4.2. Conduct stable isotope analysis of food web components to help
determine energy sources and pathways in the riverine communities
For stable isotope sample processing, algae samples were treated with 1 M HCl solution to
remove inorganic carbonates that may affect sample δ13C values. All invertebrate samples,
salmon carcass tissue, and salmon eggs were treated with a chloroform-methanol solution to
remove lipids from fatty tissues that typically have more variable and depleted δ13C signatures
relative to other tissue types (Sotiropoulos et al. 2004), and that may ultimately affect the
comparability of isotopic values of samples with varying lipid content.
For stable isotope data analysis, a combination of two- and three-way ANOVAs were performed
to determine whether mean δ13C values of benthic algae, benthic organic matter, and organic
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matter drift differed between macrohabitat types, along an upstream to downstream gradient, and
across seasons.
Most aquatic invertebrates (e.g., Plecoptera, Ephemeroptera) do not feed beyond their aquatic
juvenile life stages, so adult insects of aquatic origin were combined with aquatic larval
invertebrates in their respective functional feeding group composite samples for stable isotope
analysis. The mean δ13C isotopic signatures of composite functional feeding group samples from
each sampling site and event were compared using a three-way ANOVA to determine whether
energy sources differed between invertebrate functional feeding groups.
A Bayesian stable isotope mixing model (MixSIAR; Stock and Semmens 2013) was used to
determine the relative contributions of terrestrial, freshwater, and marine diet sources to target
fish species and age class. Diet proportions were then compared between macrohabitat types,
along an upstream to downstream gradient, and across seasons. Aquatic invertebrate samples
from each functional feeding group were lumped into an overarching “freshwater” diet source
for use in the mixing models since there were no significant differences between functional
feeding group δ13C values within each sampling site. Other diet source inputs for the mixing
models were “terrestrial”, which included all invertebrates of terrestrial origin found at each site,
and “marine”, which included spawning salmon carcass and egg tissue. Variability in the diet
composition for each focal species and age class was also estimated based on the stable isotope
mixing model results.
2.5. Characterize the invertebrate compositions in the diets of
representative fish species in relationship to their source
(benthic or drift component)
Diet composition data were summarized in terms of diet proportions by dry mass, the most
relevant metric for energy flow and food web studies (Chipps and Garvey 2007) and were
calculated for each fish and summarized under five broad categories: fish eggs, fish, aquatic
invertebrates, terrestrial invertebrates of aquatic origin (e.g., adult chironomid midges with an
aquatic larval stage), and terrestrial invertebrates of terrestrial origin (e.g., ants and caterpillars).
The wet mass of fresh salmon eggs was estimated from a length-weight relationship from the
literature (Fleming and Ng 1987). The wet mass of prey fish was estimated based on taxon-
specific length-mass relationships calculated from fish measured and weighed by the Fish
Distribution and Abundance in the Middle and Lower Susitna River Study (Study 9.6.). The dry
mass of fish and fish eggs were estimated from wet masses using percent dry mass values of
24.9% for Oncorhynchus spp., 22.5% for sculpins, and 40% for fresh salmon eggs (Ashton et al.
1993; Brey et al. 2010). The resulting dry mass values estimated for fish and fish eggs were
similar to dry mass values measured directly for similarly sized salmon fry, sculpins, and salmon
eggs in other Alaskan rivers (M. Wipfli, unpublished data).
Diet composition data from Chinook salmon and coho salmon were analyzed using MANCOVA
(multivariate analysis of covariance) to identify spatial, temporal, and ontogenetic patterns.
Rainbow trout diet data were analyzed graphically, but not statistically due to the small sample
size (n = 31 non-empty stomach content samples) and an unbalanced allocation of samples
among sampling strata. Diet proportion data from Chinook salmon and coho salmon were
arcsine-square root transformed to meet the assumption of normality (Chipps and Garvey 2007).
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The transformed diet proportions of five prey categories were specified as response variables in
separate MANCOVA models for each species. Each model tested for fixed effects of season,
focus area, and habitat type, with fork length as a covariate, using a significance level (alpha) of
0.05.
2.6. Estimate benthic macroinvertebrate colonization rates in the
Middle Susitna River Segment under pre-Project baseline
conditions to assist in evaluating future post-Project changes
to productivity in the Middle Susitna River.
Colonization samples were collected with Hester-Dendy multiplate samplers during the August-
September 2013 time period in Focus Area 104 (Whiskers Slough). Samples were shipped to
and processed by Ecoanalysts, Inc. (Moscow, Idaho) using the same methods used for benthic
samples from the Susitna River samples collected (Barbour et al. 1999; Major and Barbour
2001). Data received was prepared same as for benthic macroinvertebrate samples, as detailed in
Section 2.1.
3. RESULTS
The following results were developed based on data collected in 2013 and processed by a
taxonomic laboratory from late summer 2013 to spring 2014. Because this represents one year
of a two-year study, we caution the reader in drawing rigid conclusions regarding trends evident
in this data set. Additional data collection is ongoing for the trophic and fish diet objectives in
2014 and further data will be collected in 2015 to describe the benthic community. After two
years of study data are available, the data will be analyzed together for completion of study
objectives. The 2013 results for algal sampling are presented in the ISR 9.8.5.2 and 9.8.5.4 and
are not repeated herein
3.1. Characterize the pre-Project benthic macroinvertebrate and
algal communities with regard to species composition and
abundance in the Middle and Lower Susitna River
A total of 271 Hess samples and 70 petite Ponar grab samples were collected from the 20 study
sites and submitted to the taxonomy laboratory in 2013 (Table 3.1-1). Processed sample results
were used to calculate an assortment of metrics for each site for each index event period. For
simplicity, metric results are presented in the broader descriptive classes as discussed in the
methods section for each study station. Summary results (range, average, and median metric
scores) for each study site are presented in Tables 3.1-2 through 3.1-4.
Mean values for all metrics calculated for the River Productivity study sites in each seasonal
event are presented in Appendix A (Tables A3.1-1 through A3.1-15.) Results for mean density,
mean taxa richness, and mean EPT richness are graphically presented in Figures 3.1-1 through
3.1-15.
In 2013, benthic densities were higher overall in off-channel sites compared to main channel and
side channel sites. Upland sloughs and side sloughs in the Middle Reach had among the highest
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averaged densities (7,024 – 10,542 individuals/m2) (Tables 3.1-2 and 3.1-3). Overall densities
were also higher at tributary mouths compared to those recorded for main channel habitats,
ranging from an average 1,996 individuals/m2 at a small unnamed tributary at RP-173-1 to 5,425
individuals/m2 at the mouth of Whiskers Creek.
Overall benthic taxa richness during 2013 was highest in tributary mouths, followed by off-
channel habitats (side sloughs and upland sloughs). The EPT and chironomid taxa richness were
higher in tributaries and slough habitats, as well. Exceptions were at sites RP-173-3 and RP-
141-2, two side channel habitats that experienced reduced flows from the main channel during
the summer and fall months, making them in many ways more similar to side slough habitats
(Tables 3.1-2 and 3.1-3).
The higher taxa richness measures in tributary mouths and off-channel habitats were also
reflected in higher diversity scores, often exceeding an overall average score of 2.00.
Chironomid taxa contributed 50-percent or more to the average taxa richness at all 2013 sites,
with the exception of the Montana Creek main channel and side channel sites during the summer
and fall event periods, which showed a greater contribution of EPT taxa to the mean taxa
richness in summer and fall (Table 3.1-4).
Overall benthic community composition measures revealed that all sites were dominated by the
three most abundant taxa present in samples, averaging around 60- to 75-percent of the relative
abundance. The dominance of the top three taxa tended to be lower in tributary mouth habitats,
but were still greater than 50-percent overall. Relative abundances of chironomids to the benthic
communities were generally 50-percent or higher at most sites below Devils Canyon (Tables 3.1-
3 and 3.1-4). Sites above Devils Canyon showed overall relative abundances around 32- to 46-
percent, with the exceptions of sites RP-173-3 and RP-173-4, a side channel and side slough that
both experienced reduced flows during the summer and fall event periods (Table 3.1-2).
The contribution of EPT taxa to community compositions appeared to be less determined by
macrohabitat types. Sites within the three uppermost stations (FA-184, FA-173, and FA-141)
had notable relative abundances of EPT taxa that averaged around 20- to 25-percent at both main
channel and off-channel sites; however, upland slough sites averaged less than 1-percent overall
(Tables 3.1-2 and 3.1-3). Also, the mouths of larger tributaries (Indian River, Tsusena Creek,
Montana Creek) tended to have greater contributions of EPT to the overall community
compositions than did the smaller tributaries (Whiskers Creek, unnamed creek in FA-173). Sites
within FA-104 (Whiskers Slough) showed relative abundances of EPT of around 7-percent with
the exception of the side channel site, RP-104-5, which was an extensive shallow riffle area
throughout the 2013 study season (Table 3.1-3). In the Lower Reach, at RP-81 (Montana
Creek), the relative abundances of EPT taxa were sizeable, reaching as high as 55-percent in the
side channel site RP-81-4 (Table 3.1-4).
3.1.1. RP-184 (Watana Dam)
At the Watana Dam station, estimates of the mean macroinvertebrate density (individuals/m2)
were noticeably higher at the mouth of Tsusena Creek (RP-184-1), ranging from 3,284.5
individuals/m2 in the spring to 2,114 individuals/m2 in the summer (Figure 3.1-1). In contrast,
mean density at the side channel and main channel sites (RP-184-2 and 184-3, respectively)
ranged from 125.6 individuals/m2 in the spring to 646.5 individuals/m2 in the fall at RP-184-2.
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Mean taxa richness measures show a similar trend, with the tributary mouth averaging
approximately 25 taxa in the spring and summer, and 19 in the fall, the main channel and side
channel sites showing mean taxa richness ranging from 5.8 to 9.4 taxa (Figure 3.1-2). Mean EPT
taxa richness was nearly three times higher at the mouth of Tsusena Creek compared to the main
and side channel sites in the spring and summer event periods, with equal contributions of
mayfly and stonefly taxa (Figure 3.1-3).
3.1.2. RP-173 (Stephan Lake Complex)
Within the RP-173 station, mean density estimates typically increased over the open water period
and did not exceed 6,000 individuals/m2. One exception was the side slough macrohabitat site
(RP-173-4), where densities ranged from a low of 7,391.5 individuals/m2 during the fall to a
high of 28,720 individuals/m2 during the summer (Figure 3.1-4). In contrast, mean density
estimated at the main channel (RP-184-2) ranged from 95.3 individuals/m2 in the spring to
1,095.3 individuals/m2 in the fall.
Mean taxa richness measures were similar among RP-173 sites, with the tributary mouth, side
channel, and the side slough sites maintaining around 21.8 to 26.8 taxa (Figure 3.1-5). The main
channel site had a mean taxa richness ranging from 5.2 and 5.8 taxa in the spring and summer,
with an increase to 12.4 taxa in the fall (Figure 3.1-5). Mean EPT taxa richness was higher at the
tributary mouth (RP-173-1) as compared to other sites during the summer, but were comparable
to the side channel and side slough sites in the spring and fall event periods (Figure 3.1-6).
Chironomid taxa contributed 50-percent or more to the average taxa richness at sites within RP-
173.
3.1.3. RP-141 (Indian River)
Mean density estimates were highest at RP-141 (Indian River), with nearly 20,000
individuals/m2 recorded in the spring and summer in the upper extent of the upland slough site
(RP-141-4) (Figure 3.1-7). Mean density estimates at the main channel site (RP-141-3) did not
exceed 135 individuals/m2 (Figure 3.1-7). Mean densities at the mouth of Indian River (RP-141-
1) were approximately 1,300 to 1,400 individuals/m2 in the spring and fall event period, peaking
to 4,705 individuals/m2 during the summer event.
Mean taxa richness measures were similar among sites, with the tributary mouth, side channel,
and the upland slough sites supporting 14 to 19 taxa. The mouth of Indian River was an
exception with a summer mean taxa richness that well-exceeded other sites at 28.2 taxa (Figure
3.1-8). The main channel site was taxa-poor, with a mean taxa richness of approximately 4 taxa
in the spring and fall, and 7.24 taxa during the summer (Figure 3.1-8). Mean EPT taxa richness
was higher at the Indian River mouth (RP-141-1) than other sites during the summer and fall, but
comparable to the side channel (RP-141-2) in the spring event period, with largely mayfly and
stonefly taxa (Figure 3.1-9). Chironomid taxa contributed 50-percent or more to the average taxa
richness at sites within RP-141.
3.1.4. RP-104 (Whiskers Slough)
At RP-104 (Whiskers Slough), mean densities in the main channel and side channel sites did not
exceed 221 individuals/m2 during 2013 and were much lower compared to off-channel sites,
where estimates ranged from 1,420.8 individuals/m2 in the upland slough site (RP-104-4) during
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the spring, to 21,695.3 individuals/m2 in Whiskers Slough (RP-104-2) during the summer
(Figure 3.1-10). Mean density estimates for the off-channel habitat sites were lower during the
spring event, but increased noticeably in the summer and fall event periods (Figure 3.1-10).
Mean taxa richness measures also was higher within off-channel sites as compared to the main
channel sites. The tributary mouth site (RP-104-1) maintained the highest mean taxa richness,
ranging from 24 taxa in the spring to 27.2 taxa in the summer (Figure 3.1-11). Mean taxa
richness in the side slough (RP-104-2) increased from a low of 12.4 taxa during the spring, to a
high of 38 taxa during the fall. The main channel and side channel sites showed mean taxa
richness ranging from 2.6 taxa in the summer to 7.8 taxa during the spring (Figure 3.1-11).
Mean EPT taxa richness was higher in the tributary mouth (RP-104-1) and side slough (RP-104-
2) sites than the other three sites (Figure 3.1-12).
3.1.5. RP-81 (Montana Creek)
A contrast between main channel and off-channel macrohabitat was also seen at Station RP-81
(Montana Creek). Mean density estimates in the upland slough site (RP-81-1) and the mouth of
Montana Creek (RP-81-2) ranged from 1,074.4 to 7,579.1 individuals/m2 over the study period.
These densities were higher than mean density estimates at the main channel site (RP-81-3) and
side channel sites (RP-81-4), which ranged from 7.0 to 616.3 individuals/m2 (Figure 3.1-13).
Mean taxa richness measures also were higher within off-channel macrohabitats as compared to
main channel macrohabitats in Montana Creek. The tributary mouth site (RP-81-2) maintained
the highest mean taxa richness, ranging from 21.2 taxa in the spring to 31.6 taxa in the summer
event (Figure 3.1-14). Mean taxa richness in the side slough (RP-81-1), sampled with Ponar
grabs, ranged from a low of 9 taxa during the summer event, to a high of 26.8 taxa during the fall
event. The lower estimates at main channel and side channel sites ranged from 0.6 taxa in the
summer to 9.6 taxa during the fall (Figure 3.1-14). Mean EPT taxa richness was higher at the
tributary mouth (RP-81-2) than the other three sites, with contributions from all three EPT orders
(Figure 3.1-15).
3.2. Estimate drift of benthic macroinvertebrates in selected
habitats within the Middle and Lower Susitna River to assess
food availability to juvenile and resident fishes
A total of 92 drift net samples and 85 plankton tow samples were collected from the 20 study
sites and submitted to the taxonomy laboratory in 2013 (Table 3.2-1). Processed sample results
were used to calculate an assortment of metrics for each site for each index event period.
Summary results (range, average, and median metric scores) for each study site for a selection of
metrics are presented in Tables 3.2-2 through 3.2-4. For simplicity, metric results are presented
in the broader descriptive classes as discussed in the methods section for each study station.
Mean values for all drift net and plankton tow metrics calculated for the River Productivity study
sites are presented in Appendix A (Tables A3.2-1 through A3.2-10). Results for mean drift
density and plankton tow density are graphically presented in Figures 3.2-1 through 3.2-5.
Overall estimates within the study sites in 2013 revealed higher densities per cubic foot (ft3) of
water in sites characterized as non-flowing habitats that were sampled with plankton tows
compared to flowing water habitats that were sampled with the drift nets. Upland sloughs and
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side sloughs showed among the highest overall averaged densities via plankton tows (1.27 – 9.75
individuals/ft3) in the study year (Tables 3.2-2 through 3.2-4). For flowing habitats, mouths of
the larger tributaries (RP-184-1, RP-141-1, RP-81-2) showed higher overall drift densities as
compared nearby main channel and side channel sites.
Overall drift taxa richness during 2013 was highest in tributary mouths, followed by main
channel habitats; fewer taxa were captured in plankton tows taken in off-channel habitats (side
sloughs and upland sloughs) (Tables 3.2-2 through 3.2-4). Both the EPT taxa richness and
overall chironomid taxa richness were higher in tributaries and main channel habitats than in the
slough habitats. The higher taxa richness in tributary mouths and main channel habitats were
also reflected higher diversity scores for these habitats; diversity often exceeded an overall
average score of 2.00 (Tables 3.2-2 through 3.2-4).
In 2013, drift community composition measures revealed the relative abundance by the three
most abundant taxa present averaged between 45- to 78-percent for most sites. The dominance
of the top three taxa tended to be higher in upland and side sloughs as compared to other
habitats. Sites above Devils Canyon showed community compositions largely comprised of
chironomids, with smaller relative abundances of EPT (averages ranging from 0.9- to 11-
percent) and zooplankton (many sites averaging 11- to 12-percent) (Table 3.2-2). At sites below
Devils Canyon, flowing water sites (tributary mouths, main channels, and side channels)
displayed communities mostly composed of chironomids and a sizeable contribution of EPT,
whereas slow-water habitat sites were comprised of chironomids and a larger relative abundance
of zooplankton, especially at upland slough sites (Tables 3.2-3 and 3.2-4). One notable
exception was the unusually high EPT relative abundance estimate at RP-141-5 (70.5 percent), a
site established immediately upstream of the mouth of Indian River (Table 3.2-3). Due to a
backwater effect at this site, little flow passed through the drift nets and very low drift densities
were recorded. The relative abundance estimates were based upon an overall low numbers of
invertebrates captured and thus produced the abnormally high percentage value.
3.2.1. RP-184 (Watana Dam)
Mean drift densities were higher at the mouth of Tsusena Creek (RP-184-1), where they
increased tenfold from 0.125 individuals/ft3 during the summer to 1.25 individuals/ft3 in the fall
(Figure 3.2-1). In contrast, both the side channel and main channel sites showed consistently low
drift densities below 0.10 individuals/ft3; the only exception was a main channel site that had a
mean drift density of 0.268 individuals/ft3 during fall. Mean taxa richness also was considerably
higher in the drift at the tributary mouth, showing an average of 41.5 taxa in the summer and
dropping to 12.5 taxa in the fall. Mean taxa richness for the main channel and side channel sites
averaged around 24.4 taxa in the spring and fall, but averaged only 7 to 8 taxa in the summer.
EPT taxa richness followed a similar trend, with higher numbers of EPT taxa collected at the
tributary mouth until the fall event period. Community compositions for drift at RP-184 show
that samples were largely comprised of chironomids in the spring and summer event periods.
During the fall period, drift compositions shifted to higher contributions of simuliids (Other
Diptera), zooplankton, and other non-insect taxa.
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3.2.2. RP-173 (Stephan Lake Complex)
At RP-173, drift densities for the tributary mouth, main channel, and side channel sites ranged
from 0.037 to 0.188 individuals/ft3 (Figure 3.2-2). Plankton tow density measured at the side
slough site and within the side channel site during fall ranged from 0.427 to 4.25 individuals/ft3.
Mean taxa richness was high in drift net samples, with the tributary mouth site showing the
highest average of 51.5 taxa in the spring and dropping to 30.5 taxa in the fall. Mean taxa
richness for the main channel site averaged around 24.8 taxa overall, whereas the side channel
site showed a spring average of 30.5 taxa before dropping to an average of 3 taxa during the
summer and fall. In contrast, plankton tows in the side slough site ranged from a low of 1.8 taxa
in the fall, to 8.8 taxa during summer. Drift net samples also collected higher numbers of EPT
taxa than plankton tows, ranging from an average of 3 to 9 taxa, in comparison to 0.0 to 0.4 taxa
for plankton tows.
Community compositions for drift and plankton tows show that samples were largely comprised
of chironomids. Plankton tows collected in the side slough site also showed a notable
contribution of zooplankton, ranging from an average of 11.8-percent to 13.42-percent. Drift net
samples consistently collected higher proportions of mayflies and stoneflies compared to
plankton tows, with a higher contribution of simuliids (Other Diptera) showing up during the
fall.
3.2.3. RP-141 (Indian River)
Drift densities in the RP-141 mouth, main channel, and side channel sites, and ranged from 0.011
individuals/ft3 to 0.653 individuals/ft3 (Figure 3.2-3). Plankton tow density was measured at the
upland slough site in the slow-water habitat, revealing densities of 0.393 to 2.64 individuals/ft3,
and additionally within the side channel site during the fall event due to lower flow conditions,
which collected 0.038 individuals/ft3. Mean drift taxa richness was high overall, with the
tributary mouth site showing an average of 41 taxa for the sampling seasons as well as the
highest taxa richness within the side channel site with an average of 47 taxa. As flow levels
receded over the course of the sampling season, mean taxa richness in the side channel dropped
to 19.5 taxa in summer, and again to 0.6 taxa in the fall. Mean taxa richness for the main
channel site averaged around 15 taxa overall, ranging from 10 taxa in the spring to 21.5 taxa
during the fall event. In contrast to drift taxa richness, plankton tows resulted in generally lower
taxa richness. For example, in the upland slough site, taxa richness ranged from a low of 3 taxa
in the summer to 9.2 taxa during the spring. Drift net samples also collected higher numbers of
EPT taxa (average of 3 to 11.5 taxa) than plankton tows (average of 0.0 to 0.6 taxa).
Community compositions for drift and plankton tows show that samples were largely comprised
of chironomids. Plankton tows collected in the upland slough had a notable contribution of
zooplankton, ranging from an average of 6.2-percent in the summer to 53.2-percent during the
spring. Drift net samples consistently collected higher proportions of mayflies and stoneflies,
and Other Diptera (generally simuliids) as compared to plankton tows.
3.2.4. RP-104 (Whiskers Slough)
Mean drift density estimates for the RP-104 station at Whiskers Slough were calculated for the
mouth of Whiskers Creek, side slough, main channel, and side channel sites, and ranged from
0.02 individuals/ft3 to 0.101 individuals/ft3 (Figure 3.2-4). Plankton tows were utilized at the
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upland slough site in slow-water habitat, and additionally within the side slough site during the
summer and fall events, and within the side channel site during the fall event, due to lower flow
conditions at those locations. Plankton tow densities ranged from 1.125 to 18.48 individuals/ft3
in the upland slough, from 0.189 to 5.420 individuals/ft3 in the side slough in the summer and
fall event periods, and showed a lower density of 0.035 individuals/ft3 in the side channel in the
fall event period (Figure 3.2-4). Mean taxa richness was higher in the drift net samples, with the
tributary mouth site showing an overall average of 21.67 taxa for the sampling seasons, and the
highest taxa richness within the station. Mean taxa richness for the main channel site averaged
around 13.67 taxa overall, ranging from 7 taxa in the summer to 17.5 taxa during the fall event
period. In contrast, plankton tows in the upland slough site ranged from a low of 3.6 taxa in the
spring, to 15.6 taxa during the summer event period. Drift net samples also generally collected
higher numbers of EPT taxa than plankton tows, ranging from an average of 1.5 to 7 EPT taxa,
in comparison to 0.0 to 0.8 EPT taxa for plankton tows.
Community compositions for drift and plankton tows in RP-104 reveal a wide variety of taxa
represented in the water column. Chironomids were often dominant in both drift and plankton
samples, but no discernable trend or pattern is immediately apparent. Plankton tows collected in
the upland slough site also showed a notable contributions of zooplankton, ranging from an
average of 42.9-percent in the fall to 72.8-percent during the spring event period. Drift net
samples collected higher proportions of mayflies and stoneflies, and Other Diptera (generally
simuliids) throughout the three seasons, compared to plankton tows.
3.2.5. RP-81 (Montana Creek)
Drift densities were calculated for the mouth of Montana Creek, main channel, and side channel
sites and ranged from 0.02 to 0.252 individuals/ft3 (Figure 3.2-5). Drift samples collected during
the summer period at the tributary mouth site (RP-81-2) were lost in transit from the field, so no
results were available for that site/event period. Plankton tows were utilized at the upland slough
site (RP-81-1) in slow-water habitat for the spring and summer event periods; however, lower
flows created riffle habitat at that site in the fall so drift nets were used instead. Plankton tow
densities averaged 4.98 individuals/ft3 in spring event period at RP-81-1, and 7.96 individuals/ft3
in the summer event period (Figure 3.2-5). Drift samples within RP-81-1 in the fall averaged
0.204 individuals/ft3.
Mean drift taxa richness was high, with the tributary mouth site showing an average of 35 taxa in
spring, and an average of 44.5 taxa in fall. Mean taxa richness for the main channel site
averaged around 25.2 taxa overall, ranging from 18 taxa in spring to 29 taxa in fall. Taxa
richness for the side channel site (RP-81-4) averaged 19.7 taxa overall, whereas the side channel
site established just upstream from the tributary mouth averaged 25.5 taxa overall. In contrast,
taxa richness in plankton tows was lower. For example, zooplankton taxa richness in the upland
slough site averaged 9.2 taxa in spring and 5.6 taxa in summer. When the upland slough area
was sampled for drift in the fall, taxa richness averaged 20.5 taxa. Similar to overall taxa
richness, spring average EPT taxa was higher in the tributary mouth than other habitats, but
increased to comparable levels within the main channel and side channel sites in the summer and
fall.
Community compositions for drift and plankton tows in RP-81 revealed a wide variety of taxa
represented in the water column. As compared to plankton tows, drift samples often were
dominated by chironomids and had higher proportions of mayflies and stoneflies, and Other
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Diptera (generally simuliids) throughout the seasons. Plankton tows collected in the upland
slough site also showed notable contributions of zooplankton and other non-insect taxa (typically
ostracods, oligochaete worms, and water mites), although zooplankton and non-insect taxa were
also prevalent in drift net samples during the fall.
3.3. Conduct a feasibility study in 2013 to evaluate the suitability of
using reference sites on the Talkeetna River to monitor long-
term Project-related change in benthic productivity.
A total of 30 Hess samples, 15 petite Ponar grab samples, 12 drift net samples, and 10 plankton
tow samples were collected from three sites established on the Talkeetna River and submitted to
the taxonomy laboratory in 2013 (Tables 3.3-1 and 3.3-2). Processed sample results were used
to calculate an assortment of metrics for each site for each index event period. Summary results
(range, average, and median metric scores) for a selection of metrics at the Talkeetna sites are
presented in Tables 3.1-4 and 3.2-4. For simplicity, metric results are presented in the broader
descriptive classes as discussed in the methods section for each study station. Mean values for
all benthic, drift net, and plankton tow metrics calculated for the Talkeetna study sites are
presented in Appendix A (Tables A3.3-1 through 3.3-5). Results for mean density, mean taxa
richness, mean EPT richness, and mean drift and plankton tow densities are graphically
presented in Figures 3.3-1 through 3.3-4.
For the Talkeetna River station (RP-TKA), mean density estimates were lower in the side
channel site as compared to the two off-channel sites established. The side channel site (RP-
TKA-1) showed estimates ranging from around 550 individuals/m2 in the spring and fall event
periods, to 821 individuals/m2 in during the summer event (Figure 3.3-1). Mean density
estimates for the upland slough site (RP-TKA-2), sampled by Ponar grab, ranged from a high of
6,699.5 individuals/m2 in spring to a low of 1,145.3 in summer. The side slough site (RP-TKA-
3) mean density estimates were highest in spring (13,040 individuals/m2), and decreased
noticeably in the summer and fall (Figure 3.3-1).
Mean taxa richness measures revealed higher numbers of taxa within the side slough site in
comparison to the side channel and upland slough sites. The side slough site maintained the
highest mean taxa richness, averaging 25.5 taxa overall, and ranging from an average of 20.4 to
28.4 taxa (Figure 3.3-2). Mean taxa richness in the side channel (RP-TKA-1) averaged 11.9 taxa
over the course of the seasons, while at the upland slough site, taxa richness changed over the
seasons, ranging from a low 8.6 taxa in summer to 17.4 taxa in fall event (Figure 3.3-2). Similar
to taxa richness, EPT taxa richness also was higher at the side slough site (RP-TKA-3) with
contributions from all three EPT orders and indicated an increased presence of caddisflies in the
community, especially during the fall (Figure 3.3-3).
Community composition within RP-TKA was largely dominated by chironomids, resulting in
high contributions of collector-gatherers. Both the side channel and side slough sites also had
varying contributions of mayflies and stoneflies throughout the seasons, which was reflected in
the functional feeding group compositions as increased scraper, shredder, and predator feeding
strategies. Community composition at the upland slough site (RP-TKA-2) was primarily
comprised of chironomids and non-insect taxa (oligochaete worms), with notably no EPT taxa
contributions.
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Drift densities were calculated for both the side channel and side slough sites, and ranged from
0.041 to 0.121 individuals/ft3 (Figure 3.3-4). Plankton tow density was measured at the upland
slough site in the slow-water habitat, revealing densities of 0.960 to 1.87 individuals/ft3. Mean
taxa richness was considerably higher in the drift net as compared to plankton tow samples. The
side channel site showing an average of 21 to 27 taxa. The side slough site revealed an average
of 31 taxa in spring, 40.5 taxa in summer, and declined to an average of 18.5 taxa in fall. In
contrast, plankton tows in the upland slough site ranged from a low of 4.2 taxa in summer, to 5.4
taxa in the spring and fall. Drift net samples also collected higher numbers of EPT taxa than
plankton tows, ranging from an average of 5 to 8.5 taxa, in comparison to 0.2 to 0.6 taxa for
plankton tows.
Community compositions for drift and plankton tows show that samples were largely comprised
of chironomids. Plankton tows collected in the upland slough site also showed a notable
contribution of zooplankton, ranging from an average of 23-percent to 29.1-percent during the
study seasons. Drift net samples collected higher proportions of mayflies and stoneflies
throughout the three seasons, with a higher contribution of caddisflies during the summer and
fall event periods, compared to plankton tows.
3.4. Conduct a trophic analysis, using trophic modeling and stable
isotope analysis, to describe the food web relationships in the
current riverine community within the Middle and Lower
Susitna River
3.4.1. Develop a trophic model to estimate how environmental factors and food
availability affect the growth rate potential of focal fish species under
current and future conditions
3.4.1.1. Growth rates of salmon
Juvenile Chinook and coho salmon in the Middle and Lower River exhibited distinct size modes
when fish captured at all sites were combined (Figures 3.4-1 and 3.4-2). Ninety-five Chinook
salmon and 114 coho salmon were aged from scales to determine size-at-age relationships for
both species (Figures 3.4-3 and 3.4-4). The samples of aged fish ranged from 50-165 mm FL for
Chinook salmon and 48-119 mm for coho salmon. This size range only partially overlapped
with the apparent age-0 size modes visible in the length-frequency histograms; therefore, we
used the length-frequency data with corroborating information from previous studies on the
Susitna River (Roth and Stratton 1985; Roth et al. 1986) to determine the size of age-0 fish. We
interpreted the sizes of the age-0 fish aged from scales as indicating the upper limit of the age-0
size distribution.
The growth rates of Chinook salmon appeared to vary between the RP-104 (Whiskers Slough
Complex) and RP-141 (Indian River) sampling stations (Figures 3.4-5 through 3.4-7). In June,
the modal size of age-0 Chinook salmon was 50 mm FL at RP-104, while the modal size of fish
captured at RP-141 (Indian River) was only 35 mm. However, the Chinook salmon at RP-104
appeared to grow slowly, reaching only 55 mm by September (Figure 3.4-7). In contrast, in
September, the modal size of age-0 Chinook salmon at RP-141 was 80 mm (Figure 3.4-6). Age-
1 Chinook salmon appeared to grow from 75-95 mm between June and September at RP-104,
and from 75-105 mm during the same period at RP-141 (Figure 3.4-7). These patterns were
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corroborated by the scale data (Fig. 3.4-3). The size structure of Chinook salmon and coho
salmon captured at RP-81 were also examined, but too few fish were captured to estimate
seasonal growth.
In June, the Chinook salmon size distribution at RP-141 was trimodal, suggesting that significant
numbers of age-2 fish were present. Scale samples confirmed that these large (105-140 mm) fish
were age 2. The modal size of this age class grew from 120 mm in June to 135 mm in
September (Figure 3.4-6). By September, few age-2 fish remained at RP-141. Conversely, large
numbers of age-2 Chinook salmon were also captured at RP-104 during September, but not
during the earlier periods (Figure 3.4-5).
Coho salmon grew at similar rates in both the RP-104 and RP-141 stations, based on their size
distributions (Figs. 3.4-8 through 3.4-10). The modal sizes of age-0 coho grew from 35-40 mm
FL in June to 55-60 mm in September at both stations. The modal sizes of age-1 coho were 60-
65 mm in June and 100-105 mm in September at both stations. Few age-2 coho salmon were
identified based on size structure or scale analyses.
Ten individual passive integrated transponder (PIT) tagged Chinook salmon and four coho
salmon were measured multiple times between late July and late September 2013 at River
Productivity sampling stations, providing individual growth trajectory data. These fish exhibited
growth rates averaging 1.0-percent of their body mass per day (range: -0.09- to 2.25-percent).
Based on their sizes, most of these fish were age 1. Nearly all of these marking and recapture
events occurred in side sloughs and upland sloughs in RP-104 and RP-141.
3.4.1.2. Bioenergetics modeling
Juvenile salmon fed at markedly different rates among species, age classes, and sampling sites;
however, food intake was a primary factor limiting growth in all cases (Table 3.4-1). Among
sites with three seasons of input data, growth and consumption rates were consistently lower at
the RP-104 side slough than at the RP-141 tributary mouth. At the RP-104 side slough, age-0
Chinook salmon fed at a relatively low proportion of their maximum possible consumption rate
(P = 0.24), indicating that their growth was strongly limited by food intake. In contrast, the age-
0 Chinook salmon at the RP-141 tributary mouth fed at a higher rate of P = 0.50, indicating that
food intake was less limiting to growth. Age-0 coho salmon fed at an intermediate rate of P =
0.36 at the RP-141 tributary mouth.
The growth efficiency of juvenile salmon also varied widely, ranging from a low of 5.5-percent
for age-0 Chinook salmon at the RP-104 side slough to a high of 55-percent for age-1 Chinook
salmon at the RP-141 tributary mouth. Overall, age-1 salmon exhibited greater growth
efficiency than age-0 salmon at the same site, indicating that they met their metabolic needs with
a smaller fraction of their overall energy intake, leaving more surplus energy to allocate to
growth.
The mean mass-specific growth rates (g growth / g body mass / day) of Chinook and coho
salmon ranged from 0.29- to 2.2-percent (Table 3.4-1). This range of values was similar to the -
0.09- to 2.25-percent range of growth rates measured for individual PIT tagged fish. To achieve
these growth rates, age-0 salmon consumed 5.2- to 9.6-percent of their body weight per day on
average. Age-1 salmon consumed 2.1-percent of their body weight per day, and age-2 salmon
consumed 1.7-percent of their body weight per day, on average. Age-0 salmon at all sites and
age-1 coho salmon at the RP-104 upland slough consumed primarily aquatic insects during the
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modeled periods, while age-1 and age-2 salmon at all other sites consumed primarily fish eggs
and fish (Table 3.4-2).
3.4.2. Conduct stable isotope analysis of food web components to help
determine energy sources and pathways in the riverine communities
In 2013, a total of 1,155 tissue samples were collected for stable isotope analysis (SIA) from
multiple study components, including benthic macroinvertebrates, benthic algae, benthic organic
matter, invertebrates and organic matter in drift samples, salmon carcasses, and fin clips from
fish (Table 3.4-3).
The isotopic signatures of algae, organic matter, and spawning salmon carcasses and eggs were
well separated overall, providing a baseline with sufficient contrast to test for differences
between aquatic, terrestrial, and marine-derived energy flow to fish (Figures 3.4-11 through 3.4-
14). Large- and fine-scale spatial patterns were also present within each of these basal
endmember groups. Overall mean algal δ13C values were significantly more depleted within
study reaches below Devil’s Canyon (FA-81, mean δ13C = -28.45‰; FA-104, mean δ13C = -
28.53‰; FA-141, mean δ13C = -29.34‰) compared to the study reach above the canyon (FA-
184, mean δ13C = -23.30‰). Algal values of δ13C varied little from season to season within each
reach (P-value range: 0.108 – 0.927), but δ13C values generally varied significantly by
macrohabitat type (p < 0.001) (Figure 3.4-12). Samples collected in main channel and side
channel sites were the most similar in comparison to samples collected from other habitat types
(P = 0.848), but differed from off-channel samples. Further stratified by habitat and season,
mean algal δ13C values from samples varied the most between macrohabitat types during the
summer sampling event. Algae samples from main channel and side channel habitat types
showed more enriched δ13C values than those from upland slough, tributary mouth, and side
slough habitat types (Figure 3.4-12).
Benthic organic matter samples (Figure 3.4-13) did not show any significant differences in δ13C
values among study reaches (P = 0.710) and seasons (P = 0.360). The only significant
differences that occurred among habitat types were between samples that were collected in the
summer sampling event, but there were no apparent patterns when examining pairwise
comparisons of habitat types for this sampling event.
Organic matter drift samples (Figure 3.4-14) showed few differences in mean δ13C values
between study reaches when stratified by season. The only study reach that was consistently
different from other reaches was FA-81. No significant differences in mean δ13C values
occurred across seasons. There were no apparent patterns in mean δ13C values between habitat
types. Nearly half of all pairwise comparisons of habitat types showed significant differences.
Averaged over all sites and seasons (see Appendix A Tables A3.4-1 through 3.4-12), significant
differences existed between the mean δ13C values of all aquatic invertebrate functional feeding
groups and terrestrial invertebrates. When aquatic functional feeding groups were compared
across macrohabitat types, significant differences in mean δ13C values existed between main
channel habitats (main channel, side channel, tributary mouth) and off-channel habitats (side
slough, upland slough). Specifically, invertebrates from off-channel habitats showed more
enriched δ13C values (mean δ13C range: -28.443‰ to -33.724‰) compared to δ13C values of
invertebrates from main channel habitats (mean δ13C = -27.020‰, -27.167‰). Differences in
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mean δ13C values of aquatic invertebrates within these macrohabitat groupings were often not
significant. No significant differences existed for any invertebrate group when compared across
seasons (P-value range: 0.054 – 0.755), with the exception of shredders, which showed a shift
from summer to fall (P = 0.044).
In general, mean invertebrate δ13C differed among focus areas (P < 0.001); sample δ13C values
were most similar between FAs 81 and 141 (P = 0.047). Overall, invertebrates from FA-104
showed the most depleted δ13C values (mean δ13C = -31.028‰) while those from FA-184 were
the most enriched (mean δ13C = -26.768‰). Grazers and terrestrial invertebrates varied the least
among focus areas (no significant differences). Mean δ13C values of collector and emergent
insect samples, which consisted mostly of collectors (Chironomidae), differed the most among
study reaches. Because aquatic invertebrate functional feeding groups did not differ within each
macrohabitat type and mostly did not differ across seasons, functional feeding groups were
combined into a single aquatic invertebrate diet category for fish when running stable isotope
mixing models.
Contributions of freshwater, terrestrial, and marine diet sources to each target fish species and
age class were estimated using a Bayesian stable isotope mixing model (MixSIAR; Stock and
Semmens 2013) and compared across macrohabitat types, study reaches, and seasons. A total of
237 fish samples collected in 2013 were used in this analysis. Mixing model results suggest that
for juvenile Chinook and coho salmon, freshwater, terrestrial, and marine sources all contributed
substantially to consumer tissue. In general, marine sources were more important to both
juvenile and adult rainbow trout compared to Chinook and coho salmon.
The contribution of marine diet sources increased seasonally (Figure 3.4-15) from June to
October for Chinook, coho, and adult rainbow trout. For juvenile Chinook and coho, a peak in
terrestrial contributions occurred in the spring, whereas freshwater source contributions peaked
in the summer. Sample sizes for juvenile rainbow trout were low, however mixing model
outputs show that for the fish sampled, terrestrial sources made up the majority of the diet in the
spring, marine sources in the summer, and freshwater sources in the fall. When comparing
source contributions across study reaches (Figure 3.4-16), mixing model outputs showed similar
dietary patterns between juvenile Chinook and coho salmon. From downstream to upstream
study reaches, the contribution of marine sources to juvenile Chinook and coho increased while
that of terrestrial sources decreased. Freshwater sources were fairly similar in diets of these
species across study reaches. For juvenile rainbow trout, terrestrial sources contributed the most
to diet at FA-81 and marine contributions were greatest at FA-141. No juvenile rainbow trout
were sampled at FA-104. Adult rainbow trout tissue sampled at FA-104 showed a heavy marine
dietary influence. Contributions from terrestrial and marine sources to juvenile Chinook and
coho varied between habitat types (Figure 3.4-17), but freshwater sources varied little.
Specifically, terrestrial sources were relatively greater in both upland sloughs and side channels;
and marine sources were relatively more important in side sloughs and tributary mouths.
Juvenile rainbow trout differed greatly in source contributions between the upland slough and
tributary mouth habitats where they were sampled, with upland slough trout being heavily
influenced by a terrestrial signature and tributary mouth trout showing more influence from
marine sources. Adult rainbow trout sampled in the FA-104 side slough were heavily influenced
by marine sources.
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Mixing model outputs included measures of variability with mean diet proportions by each
covariate. These results show that seasonal effects primarily drove variation in the diets of all
fish species and life stages analyzed (see Appendix A, Figures A3.4-1 through A3.4-4).
3.5. Characterize the invertebrate compositions in the diets of
representative fish species in relationship to their source
(benthic or drift component)
Non-empty stomach contents were analyzed from 196 fish, and a total of 4,375 diet items were
identified and measured. Nearly all (> 95-percent) of the fish eggs in stomach contents were
identified as salmon eggs based on their large size (5.5-10.5 mm diameter). The prey fish
identified in stomach contents were coho salmon fry, unidentified salmonids, sculpins, and
unidentified fish ranging from approximately 4-56 mm FL. The most common aquatic
invertebrates in stomach samples (by mass) were caddisfly larvae, heptageniid mayfly larvae,
and chironomid midge larvae. The most common terrestrial invertebrates in stomach samples
were adult beetles, adult hymenopterans (ants, bees, and wasps), adult caddisflies, and adult true
flies.
The diet composition of juvenile Chinook salmon shifted ontogenetically (effect of fork length)
and differed significantly among seasons and habitat types, but not among focus areas
(MANCOVA; Table 3.5-1). The diet composition of juvenile coho salmon shifted
ontogenetically and differed significantly among seasons, focus areas, and habitat types
(MANCOVA; Table 3.5-1). The smallest fish with salmon eggs in its stomach were 59 mm FL
for coho salmon, 72 mm for Chinook salmon, and 74 mm for rainbow trout (Figure 3.5-1). The
smallest fish with fish in its stomach were 50 mm for coho salmon, 63 mm for Chinook salmon,
and 105 mm for rainbow trout (Figure 3.5-2). The smallest piscivorous fish (50-120 mm FL) ate
only small (< 20 mm standard length) unidentifiable prey fish. Rainbow trout began to consume
salmonid prey once they reached 121 mm FL, and Chinook salmon began to consume salmonids
at 123 mm FL. No coho salmon had salmonid prey in their stomach contents. All piscivorous
fish consumed only prey fish < 40-percent of their own fork length.
During spring, juvenile Chinook salmon and adult rainbow trout ate primarily fish, while
juvenile coho salmon and juvenile rainbow trout ate primarily aquatic and terrestrial
invertebrates (Figure 3.5-3). During summer and fall, juvenile Chinook salmon and juvenile
coho salmon ate large proportions of salmon eggs, with the remainder of their diets composed of
aquatic and terrestrial invertebrates. Adult rainbow trout ate primarily fish during summer and
salmon eggs during fall. Diet composition of Chinook salmon appeared to differ substantially
between focus areas RP-104 (Whiskers Creek / Slough), where salmon eggs dominated the diet,
RP-81 (Montana Creek), where invertebrates and fish made up the diet, and RP-141 (Indian
River), where fish and fish eggs made up the diet (Figure 3.5-4). However, these differences
were not statistically significant, suggesting that they may have been driven largely by seasonal
or habitat-based differences in sample size. The diet of coho salmon differed significantly
among focus areas, with similar diets of roughly 70-percent salmon eggs and 30-percent
invertebrates at RP-81 and RP-104 vs. a diet of 93-percent salmon eggs at RP-141 (Figure 3.5-4).
Additional information on diet compositions is available in Appendix A (Tables A3.5-1 through
3.5-3).
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Both Chinook salmon and coho salmon diets differed among habitat types (Figure 3.5-5).
Chinook salmon ate mostly salmon eggs in side channels and side sloughs, mostly fish in
tributary mouths, and mostly aquatic invertebrates or terrestrial invertebrates of aquatic origin in
upland sloughs. Coho salmon diets showed a similar pattern, except that they included mostly
salmon eggs, rather than fish, in tributary mouths. The rainbow trout diet data was interpreted
with caution because the sample size was unbalanced, with particular habitats sampled in certain
focus areas but not in others. Therefore, it was difficult to determine which factor drove the
observed differences in diet composition.
3.6. Estimate benthic macroinvertebrate colonization rates in the
Middle Susitna River Segment under pre-Project baseline
conditions to assist in evaluating future post-Project changes
to productivity in the Middle Susitna River.
A total of 105 Hester-Dendy samplers were collected during the 2013 test effort and submitted to
the taxonomy laboratory in 2013. Processed sample results received from the laboratory were
used to calculate an assortment of metrics for each set of samplers. Mean values for all metrics
calculated for the colonization sampler sets at each colonization site are presented in Appendix A
(Tables A3.6-1 through A3.6-4). Results for mean density and mean taxa richness are
graphically presented in Figures 3.6-1 through 3.6-8.
During the 8-week colonization test periods, samplers located at sites in main channel
macrohabitats (RP-HD-3 and RP-HD-4) were subjected to fluctuating water levels, and were
exposed for short periods of time. Flows rapidly declined during the last two weeks of the test
run, resulting in large amounts of sediment deposited at RP-HD-3, both burying and exposing all
samplers at that site. All samplers at RP-HD-3 were retrieved on September 20, 2013; to prevent
additional losses due to dewatering, all sampler sets were retrieved from RP-HD-4 the following
day, cutting the exposure times short by one week, resulting in colonization test times of 1, 3, 5,
and 7 weeks. The clear water colonization test sites located in Whiskers Slough did not
experience water level reductions as severe, and the final 1-week sampler sets were successfully
deployed and retrieved at those sites.
Results indicated that conditions were more favorable for colonization in the clear water sites.
Mean densities in the clear and warm site (HD-1) reached over 6,000 individuals/m2 by 57 days
(8 weeks), and the clear and cold site (HD-2) reached an average of approximately 4,000
individuals/m2 by the conclusion of the 8-week period (Figures 3.6-1 and 3.6-2) Average taxa
richness in the clear and warm site reached an average of 31.3 taxa in Week-4 at a deep set and
35.33 taxa at a shallow set in Week-8 (Figure 3.6-3). For the clear and cold site, peak taxa
richness reached an average of 12.67 taxa at a deep set in Week-4 and 14.33 taxa at a shallow set
in Week-8 (Figure 3.6-4).
In contrast, densities at the turbid sites were lower, with the turbid and cold site showing a
maximum average density of 171.8 individuals/m2 in a deep set colonized for 8-weeks, and the
turbid and warm site (HD-4) reaching a maximum average density of 759 individuals/m2 in a
deep set colonized for 8-weeks (Figures 3.6-5 and 3.6-6). Average taxa richness was also lower
at turbid sites as compared to clear sites, with the turbid and cold site peaking at an average of
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7.33 taxa at a deep set in Week 8 (Figure 3.6-7), and the turbid and warm site reaching a peak
average of 12 taxa at a deep set in Week 8 as well (Figure 3.6-8).
4. DISCUSSION
4.1. Benthic Macroinvertebrate and Algal Communities
Results from the 2013 benthic macroinvertebrate sampling effort, as well as the algal sampling
results given in the ISR, showed initial differences in several metrics between mainstem
macrohabitats (main channel and side channel habitats) when compared to other macrohabitat
types, especially tributary mouths and off-channel habitats (side sloughs, upland sloughs).
Tributary mouths were generally highest in mean benthic density, taxa richness, and EPT
richness, and often showed higher percentages of those EPT taxa in community compositions.
Side sloughs and upland sloughs displayed higher densities and taxa richness measures later in
the sampling season, during summer and fall. Main channel and side channel sites often
displayed the lowest density and taxa richness measures in comparison to other macrohabitats,
although exceptions were evident, especially within side channels that became more
disconnected from main channel influence, such as RP-173-3 and RP-141-2. Data from the next
year of study will be reviewed independently to see if these trends hold up over two years and/or
if different trends are evident.
The metrics calculated from the taxonomic abundance data are the first step in the data analyses
planned for the benthic macroinvertebrate data collected for this study. Benthic metrics can be
used initially to describe the benthic community structure and function, but ultimately will serve
as one of the data sets used to conduct the statistical analyses and modeling, together with the
environmental data sets collected alongside the biological data. The data collected in 2013 and
the future data collection efforts planned for 2015 will provide the information needed for the
additional statistical analyses, the results of which will be provided in the Updated Study Report.
4.2. Drift of Benthic Macroinvertebrates
Results from the drift sampling effort generally showed noticeable differences in several metrics
between mainstem macrohabitats (main channel and side channel habitats) when compared to
other macrohabitat types, especially tributary mouths and off-channel habitats (side sloughs,
upland sloughs). Tributary mouths were generally highest in mean drift density, taxa richness,
and EPT richness, and often showed higher percentages of those EPT taxa in community
compositions, especially during the spring and fall event periods. Plankton tows collected within
side sloughs and upland sloughs displayed higher densities of zooplankton and non-insect taxa,
as well as chironomids, but usually showed very low taxa richness results. Main channel and
side channel sites often displayed the lowest drift density and taxa richness measures in
comparison to tributary mouths, and those side sloughs that were able to be sampled via drift
nets.
The marked difference between drift net densities and plankton tow densities is largely attributed
to how each method samples the water volumes. Drift nets sample a significantly higher volume
of water, as it is the water moving downstream through the net itself. Invertebrates and debris
within the water column are more diluted within this large volume, and the drift net serves to
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filter a subsample of that volume. In contrast, the plankton tow net samples a much smaller
volume of water by moving through it, capturing any invertebrates and debris that are suspended
in water within its path. Invertebrates and debris within the water column are therefore more
concentrated within that limited volume, thus the higher numbers collected. So, while
invertebrate densities within an upland slough are much higher, the total volume that density can
be applied to is limited to the volume of the slough, whereas the total volume that drift density
estimate can be applied to is the volume of water in the main channel. Therefore, the
presentation of drift density and plankton tow density reflect the concentration of prey items per
cubic foot of water encountered within that macrohabitat, but does not factor in the total volumes
available. As stated for benthic samples, the data from the next year of study will be reviewed
independently from the 2013 data set to determine if the trends evident in 2013 are repeated, or if
new trends are evident.
The metrics calculated from the taxonomic abundance data are the first step in the data analyses
planned for the invertebrate drift data collected for this study. These metrics can be used initially
to describe the benthic community structure and function, but ultimately will serve as one of the
data sets used to conduct the statistical analyses and modeling, together with the environmental
data sets collected alongside the biological data. Future analyses will also include calculating
biomass estimates, and a comparison to the fish diet data also being collected for the River
Productivity Study. The data collected in 2013 and the future data collection efforts planned for
2015 will provide the information needed for the additional statistical analyses, the results of
which will be provided in the Updated Study Report.
4.3. Feasibility of Talkeetna as a Reference
Results from the benthic macroinvertebrate sampling effort on the Talkeetna River, as well as the
algal sampling results given in the ISR, generally showed noticeable differences in several
metrics between mainstem macrohabitats (the side channel habitat) when compared to the off-
channel habitats (side sloughs, upland sloughs) sampled. Side sloughs and upland sloughs
displayed higher densities and the side slough showed higher taxa richness measures during the
sampling season than were seen at the side channel site.
The metrics calculated from the taxonomic abundance data are a first step in characterizing the
structure and function of benthic communities in the Talkeetna River. These 2013 data will
undergo additional analysis that will allow for comparisons of similar macrohabitat sites on the
Susitna and Talkeetna rivers collected during the same event period. This analysis will support
an assessment of the Talkeetna River as a future reference site for evaluating Project effects
within a monitoring program, the results of which will be provided in the Updated Study Report.
4.4. Trophic Analysis of Food Web
4.4.1. Trophic Model
The growth patterns of age-0 Chinook salmon and age-0 and age-1 coho salmon in 2013 were
similar to those reported in the middle Susitna River during the 1980s, but the growth and life
history of older age classes appeared to differ from prior studies. For example, in 1984, the
average size of age-0 coho salmon grew from approximately 40 mm FL in late May to 58 mm
FL in early October. Age-1 coho salmon grew from 70 to 104 mm FL on average (Roth and
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Stratton 1985). Similar growth rates were reported in 1985 (Roth et al. 1986). These growth
rates were comparable to those reported here (Figure 3.4-10). However, the historical studies
reported that the largest juvenile salmon (> 100 mm FL) captured in the Susitna River were
mostly coho, rather than Chinook as indicated by the 2013 data. In 1984 and 1985, age-1
Chinook salmon had mostly completed their migration to saltwater by late July, and most
Chinook salmon captured during August-October were age-0. During those years, many coho
salmon reared in freshwater for two complete years and smolted at age 2. Correspondingly, the
size distribution of coho salmon captured in the river contained far more large fish > 100 mm
than did the distribution of Chinook salmon. These historical patterns were consistent with more
recent studies in the Susitna Basin and northern Cook Inlet (e.g., Moulton 1997; Davis and Davis
2009; Sepulveda et al. 2013), as well as with broad geographical patterns in juvenile salmon life
history (Taylor 1990; Quinn 2005).
In contrast, the 2013 data suggested that substantial numbers of age-1 and age-2 Chinook salmon
were present in the river through September and October, while few coho salmon were captured
after June of their age-1 year. Other data from 2013 and 2014 suggest that some Chinook
salmon in this system may exhibit a two-year freshwater residence. Chinook salmon captured in
the downstream migrant trap at the dam site, upstream of documented coho salmon habitat, were
large enough (> 100 mm FL) to potentially be age 2. Some of these large Chinook salmon may
have migrated downstream to rear in the middle river tributaries. Other possible explanations for
the discrepancy with previous studies are potential misinterpretation of the size-frequency and
scale pattern data or potential misidentification of larger coho as Chinook in the field. Expanded
genetic sampling of larger juvenile salmon during 2014 is being conducted to test the accuracy of
species identifications assigned in the field. A more robust sample size of aged fish collected in
2014 is also likely to improve the quantification of size-at-age patterns. We interpreted the data
from larger Chinook salmon (age-2s as well as age-1s sampled during August-October) with
caution until these preliminary results could be corroborated, and focused our interpretation on
the younger age classes.
The initial bioenergetics model results indicated that feeding rate was the primary factor limiting
the growth of juvenile Chinook and coho salmon, and temperature and food quality were of
secondary importance. This is consistent with general bioenergetics theory: across the range of
temperatures typically observed in Alaskan streams and rivers, the growth of juvenile Chinook
and coho salmon is expected to be limited mostly by feeding rate (Beauchamp 2009). However,
exceptions occur when temperatures are cool and food is abundant. For example, a bioenergetics
analysis and field experiment in the Chena River demonstrated that juvenile Chinook salmon fed
close to their theoretical maximum consumption rate (P near 1), and temperature was the
primary limitation on growth (Perry 2012). Likewise, heterogeneous stream temperatures in
Southwest Alaskan streams caused high variability in age-0 coho salmon growth, and these
differences were amplified by the ability of faster-growing coho to consume salmon eggs during
their first summer (Armstrong et al. 2010). A broader comparison of salmon growth and
consumption patterns across a wider range of sampling sites will be possible after the second
year of data is collected in 2014.
4.4.2. Stable isotope analysis of food web components
The 2013 isotopic analysis showed that of all endmembers analyzed, algal samples had the
greatest variability within the entire system and among study reaches (Figure 3.4-11), with the
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range of algal δ13C values overlapping that of all other subsidies (benthic and drift organic
matter, spawning salmon). The high variability in algal δ13C signatures has been documented in
other studies (Rounick et al. 1982; Doucett et al. 1996), and has been shown to vary with flow
rates and CO2 concentrations among habitats (Finlay et al. 1999). Because clear isotopic
separation of sources is required for diet studies, this variability and overlap of algal signatures
relative to other organic matter sources has made interpretation of previous studies difficult, if
not impossible (Michener and Lajtha 2007). Low sample sizes (n = 1 to 3) of algae components
at each site may also contribute to wide isotopic variability of algal signatures. Despite wide
isotopic variability of algal samples collected for this study, aquatic invertebrate δ13C values (of
all functional feeding groups) were similar to algal δ13C values from within the same site. This
consistency suggests that the algae collections in this study were successful in capturing the
variability in algal signatures.
Stable isotope mixing models suggest that both spatial and an upriver-to-downriver trends exist
in the relative contributions of freshwater, terrestrial, and marine sources. An increasing
proportion of marine sources in the diets of the target fish species from June to October suggests
that fish are foraging on energy-rich spawning salmon tissue and eggs as they become available
as a food source. These data corroborate the findings from the stomach content analysis that
juvenile Chinook and coho salmon consume substantial amounts of marine-derived food. This is
in contrast to prior juvenile salmon diet studies in the Middle Susitna Basin, which found that
these species relied almost exclusively on aquatic and terrestrial insects (ADF&G 1983; Hansen
and Richards 1985). An upriver-downriver spatial trend exists in the proportion of marine
subsidies consumed, where rearing salmon and resident trout are more heavily influenced by this
diet source higher up in the system. The opposite trend was expected; however, more spawning
salmon were observed in FA-104 and FA-141 at the time of sampling than at FA-81. The spatial
trend may therefore be explained by the overlap of suitable spawning habitats with rearing
habitats. Mixing models also suggest differences in dietary contributions between habitat types,
where foraging target species in generally clear, oxygenated tributary mouths and side sloughs
receive a greater marine subsidy compared to more turbid side channels and less-connected
upland sloughs. Again, these differences may speak to the overlap of suitable spawning and
rearing habitat.
Results from mixing models showed a consistent but partially overlapping isotopic relationship
between aquatic and terrestrial invertebrate diet sources (see Appendix A, Figures A3.4-1
through A3.4-4). Despite overlap in source signatures, mixing models were able to converge on
diet solutions for each target fish species; however, isotopic diet proportion results should be
considered in conjunction with the stomach content analysis results to gain a clearer
understanding of diet sources. Some diet items that were found in fish stomach samples, such as
non-salmon eggs and salmon fry, were not available as source inputs for isotopic analysis. The
second year of data collected in 2014 will be incorporated to increase sample sizes and develop a
more roubust trophic model.
4.5. Invertebrate composition in the diets of representative fish
species
All three study species relied heavily on salmon eggs and fish during the three sampling periods
between June and September 2013. This pattern was relatively consistent across the three focus
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areas studied and in three out of four macrohabitat types, with the exception of upland sloughs.
These diet data are interpreted with caution and focus on the broad trends in the data because of
the relatively low sample sizes. Further, the diet proportions by mass metric tends to be highly
variable when relatively unusual diet items are much larger than the average diet item in the
dataset, such as fish in these data (Chipps and Garvey 2007). The expanded fish diet sampling
program in 2014 should provide an increase in sample sizes and yield a more robust dataset for
characterizing the diet composition beyond this preliminary analysis and despite intrinsic
variability seen in 2013 data.
In contrast to these results, prior studies found that juvenile Chinook salmon and coho salmon
consumed primarily aquatic invertebrates during 1982, with very little consumption of salmon
eggs and no consumption of fish (ADF&G 1983; Hansen and Richards 1985). Direct
comparisons with the historic data are challenging because those data were presented in terms of
diet proportions by number, rather than diet proportions by mass, the metric used in this study,
which is now preferred for food web and energy flow studies (Chipps and Garvey 2007).
However, the historic data consistently show that salmon eggs were not consumed by juvenile
Chinook or coho salmon, with the exception of the last sampling event of the season on
September 23, 1982 at Indian River, when eggs comprised 6-percent of the Chinook salmon diet
and 2-percent of the coho salmon diet (proportions by number; ADF&G 1983, Appendix Tables
3-C-12 and 3-C-19). These reported proportions would likely translate to substantial proportions
by mass because the average mass of a salmon egg was 23-76 times greater than that of an
average terrestrial or aquatic invertebrate food item in the 2013 dataset. These historical data
indicate that juvenile Chinook and coho consumed salmon eggs at Indian River in late
September. However, there is no evidence that they utilized salmon eggs during other spawning
runs or at other sites within the Susitna Basin. This apparent difference may be due to increased
availability of salmon eggs to juvenile salmon, which could potentially result from small,
climate-driven changes in spawner run timing, juvenile growth to the size threshold for gape
limitation, or other factors. Alternatively, it may simply be an artifact of spatial and temporal
mismatches between the historical diet sampling events and salmon spawning runs.
4.6. Benthic Macroinvertebrate Colonization Rates
When considering the colonization test results, it is important to note that both turbid sites were
subjected to early exposures during the final week of the test period, and these lower densities
were very likely the result of that exposure. However, deep sets at HD-4 did remain inundated
for the duration of the test period, so it is reasonable to assume that turbid conditions could result
in lower densities during colonization. Water temperature appears to have an effect on the
colonization levels, with warm conditions producing higher densities and taxa richness compared
to cold conditions. The factor of water depth appeared to have little effect on the colonization of
the Hester-Dendy samplers, aside from the increased risk of dewatering and exposure in habitats
that experience frequent and significant water level fluctuations, as was seen at the turbid sites
for shallow samplers.
In test runs that were not disturbed, colonization appears to be reached at approximately six
weeks, based upon density estimates. Factoring in taxa richness measures, the clear sites
indicated that mean taxa numbers were reached as early as four weeks. However, this could be
the initial colonizing pioneer taxa, and additional time may be necessary until the community can
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be determined to be in equilibrium. For turbid conditions, the limited results suggest that a 6-8
week period may be sufficient, as well.
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5. REFERENCES
ADF&G. 1983. Susitna Hydro Aquatic Studies Phase II Basic Data Report: Resident and
Juvenile Anadromous Fish Studies on the Susitna River Below Devils Canyon, 1982.
Alaska Department of Fish and Game, Anchorage, Alaska.
Alaska Energy Authority (AEA) 2014. Initial Study Report: Susitna-Watana Hydroelectric
Project FERC Project No. 14241. June 2014. Prepared for the Federal Energy Regulatory
Comission by the Alaska Energy Authority, Anchorage, Alaska. http:///www.susitna-
watanahydro.org/type/documents.
Armstrong, J.B. 2010. Comment on “Egg consumption in mature Pacific salmon
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6. TABLES
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Table 3.1-1. Benthic macroinvertebrate sample totals for 2013 sampling during three index events (Spr= Spring, Sum=Summer, Fall) and Post-Storm sampling for sites in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Site Macrohabitat Type
Hess Samples Ponar Grab Samples
Spr Sum Fall
Post-
Storm Total Spr Sum Fall
Post-
Storm Total
RP-184-1 Tributary Mouth
(TM) 5 5 5 15 RP-184-2 Side Channel (SC) 5 5 5 15 RP-184-3 Main Channel (MC) 5 5 5 15 RP-173-1 Tributary Mouth 5 5 5 15 RP-173-2 Main Channel 5 5 5 15 RP-173-3 Side Channel 5 5 5 15 RP-173-4 Side Slough 5 5 2 5 17 5 5 5 5 20
RP-141-1 Tributary Mouth 5 5 5 15 RP-141-2 Side Channel 5 5 10 5 5
RP-141-3 Mult Split Main
Channel 5 5 5 15 RP-141-4 Upland Slough 5 4 3 12 5 5 5 15
RP-104-1 Side Slough 5 5 5 15 RP-104-2 Side Slough 5 5 2 5 17 5 5
RP-104-3 Main Channel 5 5 5 15 RP-104-4 Upland Slough 5 5 5 15
RP-104-5 Side Channel 5 5 5 15 RP-81-1 Upland Slough 5 5 5 5 10
RP-81-2 Tributary Mouth 5 5 5 15 RP-81-3 Split Main Channel 5 5 5 15 RP-81-4 Side Channel 5 5 5 15
Totals 90 89 82 10 271 20 20 25 5 70
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Table 3.1-2. Summary benthic metrics for sites at River Productivity stations in Middle Reach above Devils Canyon.
Station FA-184 (Watana Dam) FA-173 (Stephan Lake Complex)
Site RP-184-1 RP-184-2 RP-184-3 RP-173-1 RP-173-2 RP-173-3 RP-173-4
Habitat TM SC MC TM MC SC SS
Density (Individuals/m2)
Range 1337 - 5178 23.3 - 1744 58.1 - 488 244 - 4930 11.6 - 3291 826 - 9037 0 - 65116
Average 2653.0 337.2 218.6 1995.7 439.5 3664.3 9068.8
Median 2372.1 209.3 174.4 1546.5 127.9 2941.9 4821.7
Taxa Richness
Range 16 - 33 2 - 14 3 - 15 3 - 43 1 - 17 8 - 32 0 - 40
Average 22.9 7.5 7.9 23.9 7.8 23.5 16.0
Median 23 8 7 25 7 25 17
EPT Richness
Range 4 - 11 0 - 6 0 - 6 0 - 12 0 - 10 0 - 8 0 - 9
Average 6.0 2.0 2.0 7.0 3.0 5.0 2.0
Median 6 2 2 7 2 5 1
Chironomid Taxa
Range 4 - 17 0 - 6 0 - 9 1 - 20 0 - 5 5 - 20 0 - 22
Average 11.0 3.0 3.0 11.0 3.0 13.0 10.0
Median 10 4 4 12 3 13 11
Diversity (H')
Range 1.31 - 2.53 0.69 - 2.04 0.95 - 2.3 0.84 - 3.08 0 - 2.03 1.4 - 2.73 0 - 2.8
Average 1.99 1.48 1.69 2.35 1.45 2.17 1.87
Median 1.96 1.67 1.69 2.48 1.61 2.32 1.91
Relative Abundance Top 3 Taxa (Percent)
Range 50.1 - 87.3 57.5 - 100 51.3 - 100 33.7 - 100 60 - 100 46.2 - 83.3 0 - 100
Average 69.8 77.6 71.8 56.3 76.5 63.8 65.3
Median 73.7 75.1 72.9 51.6 74.1 62.9 65.9
Relative Abundance EPT (Percent)
Range 11.1 - 68.4 0 - 70 0 - 58.3 0 - 55.9 0 - 60.4 0 - 65.3 0 - 20
Average 43.5 24.3 21.3 28.4 25.0 19.7 2.7
Median 43.3 22.2 16.0 27.8 24.1 7.7 0.3
Relative Abundance Chironomids (Percent)
Range 6.2 - 88.3 0 - 100 0 - 88.9 8.4 - 74.2 0 - 100 16.7 - 90.3 0 - 100
Average 32.0 45.6 36.1 42.4 35.6 53.8 70.9
Median 26.3 50.0 40.0 53.3 27.3 52.2 77.1
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Table 3.1-3. Summary benthic metrics for sites at River Productivity stations in Middle Reach below Devils Canyon.
Station FA-141 (Indian River) FA-104 (Whiskers Slough)
Site RP-141-1 RP-141-2 RP-141-3 RP-141-4 RP-104-1 RP-104-2 RP-104-3 RP-104-4 RP-104-5
Habitat TM SC MC US TM SS MC US SC
Density (Individuals/m2)
Range 547 - 7380 116 - 2971 0 - 256 517 - 64744 326 - 12062 81 - 47132 0 - 407 258 - 21493 11.6 - 279
Average 2468.5 827.0 96.1 10541.7 5424.9 7667.1 147.3 7024.4 130.2
Median 1755.8 602.8 81.4 7220.9 4081.4 3057.0 116.3 6544.5 116.3
Taxa Richness
Range 11 - 38 3 - 29 0 - 11 4 - 22 13 - 33 6 - 41 0 - 13 3 - 32 1 - 14
Average 20.1 11.3 5.0 13.6 25.9 21.3 5.9 16.4 5.7
Median 18 10 5 14 28 20 6 17 5
EPT Richness
Range 3 - 12 0 - 10 0 - 8 0 - 5 0 - 6 0 - 6 0 - 2 0 - 1 0 - 4
Average 7.0 3.0 2.0 1.0 3.0 3.0 1.0 0.0 2.0
Median 7 2 1 0 4 2.5 0 0 2
Chironomid Taxa
Range 2 - 17 2 - 15 0 - 5 0 - 15 8 - 22 3 - 26 0 - 9 1 - 22 0 - 9
Average 8.0 6.0 2.0 9.0 16.0 14.0 4.0 12.0 3.0
Median 7 5 2 9 17 13 4 11 3
Diversity (H')
Range 1.26 - 2.42 0.51 - 3.06 0 - 2.06 0.84 - 2.57 1.77 - 2.77 1.33 - 2.7 0 - 1.91 1.04 - 2.73 0 - 2.5
Average 1.90 1.74 1.35 1.71 2.26 2.15 1.43 1.82 1.35
Median 1.97 1.84 1.45 1.73 2.27 2.1 1.63 1.79 1.39
Relative Abundance Top 3 Taxa (Percent)
Range 50.4 - 83.1 30 - 100 0 - 100 47.8 - 95.5 41.5 - 74.4 39 - 85.3 0 - 100 34.5 - 100 41.7 - 100
Average 68.9 68.6 73.2 74.8 59.2 60.5 68.7 70.1 77.4
Median 70.0 68.8 75.0 74.3 58.1 59.1 72.7 72.0 80.0
Relative Abundance EPT (Percent)
Range 13.9 - 91.1 0 - 50 0 - 66.7 0 - 6.6 0 - 32.1 0 - 42.1 0 - 28.6 0 - 6.9 0 - 75
Average 61.5 16.9 26.6 0.8 7.1 7.1 7.2 0.5 33.9
Median 73.0 10.2 28.6 0.0 4.6 4.6 0.0 0.0 33.3
Relative Abundance Chironomids (Percent)
Range 3.4 - 81.8 29.5 - 100 0 - 100 0 - 96.2 26.8 - 92 34.3 - 84.3 0 - 100 16.7 - 100 0 - 100
Average 30.5 66.5 55.2 57.6 74.4 59.2 65.2 55.7 42.2
Median 20.0 63.3 44.4 55.9 85.5 56.3 70.0 55.5 33.3
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Table 3.1-4. Summary benthic metrics for sites at River Productivity stations in Lower Reach downstream of the confluence with Chulitna River.
Station RP-81 (Montana Creek) RP-TKA (Talkeetna River)
Site RP-81-1 RP-81-2 RP-81-3 RP-81-4 RP-TKA-1 RP-TKA-2 RP-TKA-3
Habitat US TM MC SC SC US SS
Density (Individuals/m2)
Range 628 - 19576 698 - 16233 0 - 244 58.1 - 884 279.1 - 1698 129 - 13476 1895 -
18870
Average 3864.8 3996.9 111.6 284.5 637.2 4609.8 7690.0
Median 1872.1 2534.9 139.5 162.8 558.1 2669.4 5782.9
Taxa Richness
Range 6 - 26 9 - 40 0 - 10 4 - 15 9 - 17 2 - 29 14 - 32
Average 13.2 26.5 3.7 7.9 11.9 13.1 25.5
Median 10 27 3 9 11 12 26
EPT Richness
Range 0 - 2 2 - 15 0 - 5 1 - 9 3 - 9 0 - 1 5 - 13
Average 0.0 8.0 1.0 4.0 5.0 0.0 9.0
Median 0 8 0 3 5 0 10
Chironomid Taxa
Range 4 - 20 6 - 21 0 - 5 0 - 7 2 - 8 2 - 23 6 - 17
Average 9.0 13.0 2.0 2.0 5.0 10.0 11.0
Median 6 13 1 2 5 9 11
Diversity (H')
Range 1.15 - 2.6 1.13 - 3.2 0 - 1.96 1.33 - 2.25 1.45 - 2.42 0.64 - 2.59 1.58 - 2.91
Average 1.85 2.32 0.84 1.78 1.89 1.61 2.26
Median 1.65 2.44 0.72 1.67 1.80 1.61 2.31
Relative Abundance Top 3 Taxa (Percent)
Range 44.3 - 89.5 32.6 - 93.1 0 - 100 45.5 - 84.2 48.7 - 81.6 53.1 - 100 32.4 - 85.6
Average 70.6 59.4 67.9 65.0 67.3 77.0 60.8
Median 76.5 59.4 81.0 62.5 70.7 80.2 63.1
Relative Abundance EPT (Percent)
Range 0 - 2.5 4.6 - 55 0 - 68.4 9.1 - 100 11 - 70.4 0 - 0.6 10.5 - 73.9
Average 0.5 22.0 13.8 54.6 35.6 0.0 34.6
Median 0.0 20.6 0.0 60.0 29.2 0.0 23.4
Relative Abundance Chironomids (Percent)
Range 18.5 - 73.7 28.3 - 94.7 0 - 100 0 - 66.7 14.3 - 88.4 10.1 - 100 15.5 - 84.9
Average 46.2 68.0 33.1 28.3 56.1 59.4 55.9
Median 46.6 74.3 23.8 26.7 62.3 68.9 61.4
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Table 3.2-1. Benthic drift and plankton tow sample totals for 2013 sampling during three index events (Spr= Spring, Sum=Summer, Fall) and Post-Storm for sampling sites in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Site
Macrohabitat
Type
Drift Samples Plankton Tow Samples
Spr Sum Fall Total Spr Sum Fall
Post-
Storm Total
RP-184-1 Tributary Mouth 2 2 2 6
RP-184-2 Side Channel 2 2 2 6
RP-184-3 Main Channel 2 2 2 6
RP-173-1 Tributary Mouth 2 2 2 6
RP-173-2 Main Channel 2 2 2 6
RP-173-3 Side Channel 2 2
2
5
5
RP-173-4 Side Slough
5 5 5
15
RP-141-1 Tributary Mouth 2 2 2 6
RP-141-2 Side Channel 2 2 2 6
RP-141-3 Mult Split Main Channel 2 2
2
5
5
RP-141-4 Upland Slough
5 5 5
15
RP-141-5* Main Channel
2
2
RP-104-1 Trib Mouth/Side Slough 2 2 2 6
RP-104-2 Side Slough 2
2
5 5 5 15
RP-104-3 Main Channel 2 2 2 6
RP-104-4 Upland Slough 2
2 5 5 5
15
RP-104-5 Side Channel 2 2
2
5
5
RP-81-1 Upland Slough
2 2 5 5
10
RP-81-2 Tributary Mouth 2 2 2 6
RP-81-3 Split Main Channel 2 2 2 6
RP-81-4 Side Channel 2 2 2 6
RP-81-5* Side Channel 2 2 2 6
Totals 36 34 28 92 20 25 35 5 85
Note:
* = Additional site established immediately upstream of tributary mouth to address tributary mouth drift contributions.
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Table 3.2-2. Summary drift and plankton metrics for sites at River Productivity stations in Middle Reach above Devils Canyon.
Station FA-184 (Watana Dam) FA-173 (Stephan Lake Complex)
Site RP-184-1 RP-184-2 RP-184-3 RP-173-1 RP-173-2 RP-173-3 RP-173-4
Habitat TM SC MC TM MC SC SS
Density (Individuals/ft3)
Range 0.076 - 2.18 0.003 - 0.11 0.01 - 0.45 0.023 - 0.27 0.034 - 0.34 0 - 2.64 0 - 10.75
Average 0.53 0.05 0.12 0.14 0.17 0.54 1.72
Median 0.22 0.06 0.07 0.11 0.15 0.09 0.56
Taxa Richness
Range 10 - 54 7 - 28 6 - 29 26 - 55 17 - 34 0 - 32 0 - 15
Average 30.3 19.7 17.8 40.0 24.8 9.2 4.3
Median 32.50 23.50 20.00 40.50 24.50 4.00 3.00
EPT Richness
Range 2 - 9 1 - 5 0 - 5 5 - 13 2 - 9 0 - 4 0 - 1
Average 5.0 2.5 2.7 7.3 4.3 1.0 0.1
Median 5.00 2.00 2.50 6.50 4.00 0.00 0.00
Chironomid Taxa
Range 3 - 27 2 - 16 5 - 13 6 - 25 5 - 14 0 - 12 0 - 8
Average 14.2 9.7 8.2 15.7 9.7 4.0 2.5
Median 15.50 10.50 7.00 16.50 9.50 2.00 2.00
Diversity (H')
Range 0.3 - 3.12 1.88 - 2.45 1.53 - 2.14 1.92 - 3.31 1.99 - 2.87 0 - 2.76 0 - 2.29
Average 1.87 2.13 1.90 2.78 2.50 1.32 0.82
Median 1.99 2.09 1.96 3.07 2.55 1.22 0.80
Relative Abundance Top 3 Taxa (Percent)
Range 41.7 - 97.7 54.2 - 78.4 53.8 - 80.2 31.2 - 73.6 37 - 70.1 0 - 100 0 - 100
Average 69.4 63.3 69.2 47.6 53.1 69.3 78.7
Median 67.3 62.2 69.4 38.5 52.5 76.9 96.0
Relative Abundance EPT (Percent)
Range 1.5 - 10.3 1.7 - 11.1 0 - 7.7 4.5 - 22.9 4.2 - 13.5 0 - 20 0 - 8.3
Average 5.9 5.5 3.3 11.0 6.8 5.4 0.9
Median 6.1 4.8 2.8 10.0 5.0 0.0 0.0
Relative Abundance Chironomids (Percent)
Range 2.7 - 82.6 8.4 - 66.4 4.5 - 90 23.6 - 55.9 3.5 - 57.8 0 - 100 0 - 100
Average 56.6 38.9 42.4 37.8 35.9 66 69.3
Median 71.46 42.64 47.54 34.29 47.23 66.67 75.00
Relative Abundance Zooplankton (Percent)
Range 0 - 0.5 0 - 43.3 0 - 54.2 0 - 0.9 0 - 48.6 0 - 33.3 0 - 50
Average 0.1 11.7 11.6 0.3 11.8 6.1 11.3
Median 0.0 0.0 0.3 0.2 4.9 0.0 0.0
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Table 3.2-3. Summary drift and plankton metrics for sites at River Productivity stations in Middle Reach below Devils Canyon.
Station FA-141 (Indian River) FA-104 (Whiskers Slough)
Site RP-141-1 RP-141-2 RP-141-3 RP-141-4 RP-141-5 RP-104-1 RP-104-2 RP-104-3 RP-104-4 RP-104-5
Metric Habitat TM SC MC US MC TM SS MC US SC
Density (Individuals/ft3)
Range 0.18 - 0.75 0 - 0.22 0.002 - 0.08 0 - 5.36 0.009 -
0.02 0.02 - 0.06 0 - 17.07 0 - 0.15 0 - 75.23 0 - 0.17
Average 0.48 0.07 0.03 1.27 0.01 0.04 1.82 0.05 9.75 0.05
Median 0.49 0.01 0.03 0.34 0.01 0.04 0.17 0.05 4.68 0.01
Taxa Richness
Range 37 - 45 0 - 54 2 - 24 0 - 15 5 - 18 17 - 33 0 - 13 0 - 22 0 - 20 0 - 35
Average 41.0 15.1 15.0 5.4 11.5 21.7 4.7 13.7 10.5 11.0
Median 41.00 2.00 18.50 4.00 11.50 19.50 3.00 14.50 12.00 2.00
EPT Richness
Range 6 - 12 0 - 6 0 - 6 0 - 2 2 - 3 2 - 3 0 - 3 0 - 4 0 - 1 0 - 8
Average 9.5 2.1 2.2 0.3 2.5 2.8 0.6 2.3 0.2 2.2
Median 9.50 1.00 1.50 0.00 2.50 3.00 0.00 2.50 0.00 0.00
Chironomid
Taxa
Range 15 - 19 0 - 24 1 - 13 0 - 7 1 - 6 9 - 16 0 - 6 0 - 11 0 - 6 0 - 19
Average 16.3 6.0 6.7 1.6 3.5 11.7 2.0 5.0 2.5 4.8
Median 15.50 1.00 7.00 1.00 3.50 11.00 1.00 5.00 2.00 0.00
Diversity (H')
Range 1.96 - 3.08 0 - 2.97 0.64 - 2.85 0 - 2.34 0.84 - 2.07 2.17 - 2.97 0 - 1.74 0 - 2.86 0 - 2.4 0 - 2.77
Average 2.57 1.28 1.98 1.21 1.46 2.51 0.88 1.93 1.67 1.22
Median 2.60 0.69 2.08 1.33 1.46 2.54 1.10 2.10 1.97 0.64
Relative Abundance Top
3 Taxa (Percent)
Range 34 - 73.4 0 - 100 38.1 - 100 0 - 100 62.7 - 93.3 39.5 - 67.8 0 - 100 0 - 71.4 0 - 100 0 - 100
Average 54.1 43.3 62.0 78.0 78.0 50.2 71.8 45.5 56.2 33.9
Median 55.8 46.1 60.4 83.3 78.0 46.8 80.3 51.2 62.1 41.4
Relative Abundance EPT (Percent)
Range 10.6 - 38.5 0 - 50 0 - 22 0 - 7.7 51 - 90 3.3 - 26.3 0 - 66.7 0 - 24 0 - 50 0 - 62.5
Average 23.4 11.3 8.4 1.0 70.5 11.5 11.0 7.9 3.5 13.2
Median 21.0 5.7 4.3 0.0 70.5 9.8 0.0 5.9 0.0 0.0
Relative Abundance
Chironomids
(Percent)
Range 24.8 - 64.1 0 - 50 12.7 - 75.6 0 - 88 3.3 - 15.7 19.3 - 84.6 0 - 100 0 - 53.1 0 - 25 0 - 60.7
Average 44.4 23.5 41.1 28.9 9.5 54.3 43.2 25.4 11.1 18.6
Median 43.52 33.33 37.85 33.33 9.51 57.37 33.33 21.20 12.20 0.00
Relative Abundance Zooplankton (Percent)
Range 0 - 0.6 0 - 9 0 - 11.8 0 - 96.7 0 - 0 0 - 11.4 0 - 66.7 0 - 36.6 0 - 85.4 0 - 66.7
Average 0.2 1.7 2.9 31.9 0.0 3.9 15.5 10.0 52.6 8.0
Median 0.0 0.0 1.2 23.8 0.0 1.8 3.7 1.0 61.2 0.0
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Table 3.2-4. Summary drift and plankton metrics for sites at River Productivity stations in Lower Reach downstream of confluence with Chulitna River.
Station RP-81 (Montana Creek) RP-TKA (Talkeetna River)
Site RP-81-1 RP-81-2 RP-81-3 RP-81-4 RP-81-5 RP-TKA-1 RP-TKA-2 RP-TKA-3
Habitat US TM MC SC SC SC US SS
Density (Individuals/ft3)
Range 0 - 38.06 0.071 - 0.23 0.01 - 0.13 0.02 - 0.11 0.04 - 0.27 0.022 - 0.17 0 - 5.43 0.035 -
0.2
Average 5.43 0.14 0.06 0.05 0.14 0.10 1.44 0.08
Median 0.94 0.14 0.04 0.04 0.12 0.11 0.87 0.05
Taxa Richness
Range 0 - 22 35 - 51 17 - 35 8 - 27 19 - 34 20 - 28 0 - 10 17 - 47
Average 9.6 39.8 25.2 19.7 25.5 23.5 5.0 30.0
Median 8.50 36.50 23.50 19.50 23.50 22.50 5.00 31.00
EPT Richness
Range 0 - 2 5 - 9 1 - 8 1 - 9 3 - 7 5 - 7 0 - 2 4 - 9
Average 0.3 7.3 4.5 5.0 4.8 5.5 0.4 7.3
Median 0.00 7.50 4.50 5.00 4.50 5.00 0.00 8.00
Chironomid Taxa
Range 0 - 8 14 - 25 5 - 14 2 - 9 2 - 13 6 - 12 0 - 5 4 - 21
Average 2.8 17.5 9.5 5.7 7.3 9.0 2.3 12.3
Median 2.00 15.50 9.50 6.50 8.00 9.00 2.00 14.00
Diversity (H')
Range 0 - 2.04 2.48 - 3.26 2.33 - 3.32 1.77 - 3.07 1.78 - 3.14 2.47 - 2.73 0 - 2.15 2.06 -
3.06
Average 1.29 2.83 2.80 2.39 2.66 2.59 1.30 2.52
Median 1.36 2.79 2.85 2.31 2.74 2.58 1.49 2.46
Relative Abundance Top 3 Taxa (Percent)
Range 0 - 100 33.6 - 59.3 24.5 - 54.2 29.4 - 73.2 32.3 - 73.4 37.3 - 59.9 0 - 100 37.2 -
69.2
Average 76.2 47.6 40.9 49.9 46.8 50.3 72.6 54.1
Median 81.5 48.8 41.3 49.0 45.0 53.1 75.0 53.5
Relative Abundance EPT (Percent)
Range 0 - 0.9 9.3 - 18.3 2.4 - 24.7 8.1 - 79 12.9 - 44.3 16.5 - 32.5 0 - 27.3 13.6 -
64.8
Average 0.1 14.3 11.0 36.5 25.3 23.7 4.6 33.2
Median 0.0 14.9 7.1 24.3 21.9 22.9 0.0 26.2
Relative Abundance Chironomids (Percent)
Range 0 - 100 27.2 - 63 8.7 - 53.2 2.9 - 66.7 1.3 - 42.5 32.5 - 66 0 - 100 9.3 -
75.6
Average 18.1 44.9 35.1 29.2 23 47.6 48.2 49.8
Median 5.24 44.72 35.47 32.33 26.37 49.16 43.75 53.03
Relative Abundance Zooplankton (Percent)
Range 0 - 100 0 - 21 0 - 44.3 0 - 1 0 - 61.3 0 - 1.6 0 - 60 0 - 1.1
Average 46.5 8.7 8.6 0.3 17.1 0.3 27.6 0.3
Median 43.6 6.8 1.2 0.0 4.0 0.0 28.6 0.0
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Table 3.3-1. Benthic macroinvertebrate sample totals for 2013 sampling during three index events (Spring, Summer, Fall) for sites in the Talkeetna River (TKA) for the River Productivity Study.
Site Macro-habitat Type
Hess Samples Ponar Grab Samples
Spring Summer Fall Total Spring Summer Fall Total
RP-TKA-1 Side Channel 5 5 5 15 RP-TKA-2 Upland Slough 5 5 5 15
RP-TKA-3 Side Slough 5 5 5 15
Totals: 10 10 10 30 5 5 5 15
Table 3.3-2. Benthic drift and plankton tow sample totals for 2013 sampling during three index events (Spring, Summer, Fall) for sites in the Talkeetna (TKA) River for the River Productivity Study.
Site Macro-habitat Type
Drift Samples Plankton Tow Samples
Spring Summer Fall Total Spring Summer Fall Total
RP-TKA-1 Side Channel 2 2 2 6 RP-TKA-2 Upland Slough 5 5 10
RP-TKA-3 Side Slough 2 2 2 6
Totals: 4 4 4 12 0 5 5 10
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Table 3.4-1. Bioenergetics model results showing the growth, consumption rate, and growth efficiency of juvenile Chinook and coho salmon. Growth and consumption were simulated for 91-day intervals between the spring and fall sampling events (Spr-Fall) or for 31-day intervals between the summer and fall events (Sum-Fall), depending on the availability of input data.
Species Age Station Habitat
Seasons
modeled
Growth
(g wet)
Total
consumption
(g wet)
P, Proportion
of max.
consumption
Growth
efficiency
(%)
Mean mass-
specific consumption
rate
(g/g/d)
Mean mass-
specific
growth rate
(g/g/d)
Chinook 0 RP-104 SS Spr-Fall 0.40 7.21 0.24 5.5% 5.2% 0.29%
Chinook 1 RP-104 SS Spr-Fall 4.42 14.30 0.19 31% 2.9% 0.77%
Chinook 0 RP-141 TM Spr-Fall 4.48 20.44 0.50 22% 9.6% 2.2%
Chinook 1 RP-141 TM Spr-Fall 17.84 32.62 0.28 55% 3.6% 1.8%
Chinook 2 RP-141 TM Spr-Fall 7.40 30.86 0.16 24% 1.7% 0.39%
Coho 0 RP-141 TM Spr-Fall 1.79 9.91 0.36 18% 8.1% 1.5%
Coho 1 RP-141 TM Spr-Fall 9.47 18.09 0.24 52% 3.7% 1.7%
Coho 0 RP-104 SS Sum-Fall 0.58 4.01 0.35 14% 6.2% 0.92%
Coho 1 RP-104 SS Sum-Fall 1.49 6.05 0.18 25% 2.1% 0.50%
Coho 0 RP-104 US Sum-Fall 0.57 3.60 0.39 16% 5.5% 0.92%
Coho 1 RP-104 US Sum-Fall 1.42 11.14 0.40 13% 3.7% 0.50%
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Table 3.4-2. Total consumption by juvenile Chinook and coho salmon broken down by individual prey categories, as estimated by bioenergetics models. Prey categories included fish eggs, fish, aquatic invertebrates, terrestrial insects
(aquatic origin), and terrestrial insects (terrestrial origin).
Species Age Station Habitat Seasons modeled
Consumption by prey category (g wet)
Fish Eggs Fish Aq. Inverts TI (aq. origin) TI (te. origin)
Chinook 0 RP-104 SS Spr-Fall - - 5.54 1.46 0.21
Chinook 1 RP-104 SS Spr-Fall 8.89 - 4.57 0.74 0.11
Chinook 0 RP-141 TM Spr-Fall - - 18.7 0.4 1.4
Chinook 1 RP-141 TM Spr-Fall 21.79 7.77 2.13 0.64 0.29
Chinook 2 RP-141 TM Spr-Fall 18.22 9.80 1.88 0.59 0.37
Coho 0 RP-141 TM Spr-Fall - - 9.1 0.2 0.6
Coho 1 RP-141 TM Spr-Fall 12.04 4.35 1.18 0.35 0.16
Coho 0 RP-104 SS Sum-Fall - - 1.40 1.03 1.58
Coho 1 RP-104 SS Sum-Fall 3.06 0.98 0.81 0.57 0.63
Coho 0 RP-104 US Sum-Fall - - 3.18 0.41 -
Coho 1 RP-104 US Sum-Fall - - 9.86 1.27 -
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Table 3.4-3. Total stable isotope samples analyzed in 2013.
Category Component Sites Seasons Samples
Maximum
Potential
Number of
Samples Spring Summer Fall
Total Number
Analyzed (2013)
Endmembers
Benthic Algae 16 3 3 144 44 41 49 134
Organic Matter - benthic 16 3 3 144 44 48 48 140
Organic Matter - drift 16 3 2 96 30 32 32 94
Salmon carcass - - 40 40 0 12 9 21
Invertebrates
Benthic- grazers 16 3 3 144 25 24 28 77
Benthic- collectors 16 3 3 144 37 44 46 127
Benthic- shredders 16 3 3 144 19 16 36 71
Benthic- predators 16 3 3 144 36 37 32 105
Terrestrial Drift 16 3 2 96 23 30 27 80
Emergents 16 3 1 48 32 33 10 75
Fish
Chinook salmon -
juveniles 16 3 8 384 30 38 20 88
Coho salmon - juveniles 16 3 8 384 24 41 43 108
Rainbow trout -
juveniles 16 3 8 384 8 8 2 18
Rainbow trout - adults 16 3 8 384 1 9 7 17
Total 2,680 353 413 389 1,155
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Table 3.5-1. MANCOVA models testing for temporal, spatial, and ontogenetic differences in diet composition of juvenile Chinook salmon and juvenile coho salmon. Degrees of freedom (df) are listed for both hypothesis and error terms.
Factor Levels Hyp df Error df Wilk's lambda F P
Chinook salmon
Fork length (covariate) 50-165 mm 5 66 - 3.79 0.0045
Season Spring, Summer, Fall 10 132 0.506 5.36 <0.0001
Focus Area RP-81, RP-104, RP-141 10 132 0.784 1.71 0.0846
Habitat SC, SS, TM, US 15 183 0.542 3.02 0.0002
Coho salmon
Fork length (covariate) 48-119 mm 5 76 - 0.242 0.0049
Season Spring, Summer, Fall 10 152 0.785 1.96 0.0415
Focus Area RP-81, RP-104, RP-141 10 152 0.761 2.23 0.0191
Habitat SC, SS, TM, US 15 210 0.532 3.6 <0.0001
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7. FIGURES
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Figure 2.1-1. Middle Susitna River Segment, with the four River Productivity sampling stations /Instream Flow Focus Areas selected for the River Productivity Study, plus the sampling station for reference sites on the Talkeetna River.
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Figure 2.1-2. Lower Susitna River Segment, with Montana Creek area River Productivity sampling station selected for the River Productivity Study.
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Figure 3.1-1. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three
index events for sites within the Watana Dam Focus Area (FA-173) in the Middle River Segment of the Susitna River for
the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.1-2. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Watana Dam Focus Area (FA-184) in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP- 184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean Density (Individuals/m2)0
1000
2000
3000
4000
5000
Spring
Summer
Fall
Trib Mouth Main ChannelSide Channel
RP-184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean Number of Taxa Collected0
5
10
15
20
25
30
35
Spring
Summer
Fall
Trib Mouth Main ChannelSide Channel
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Figure 3.1-3. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Watana Dam Focus Area (FA-184) in
the Middle River Segment of the Susitna River for the River Productivity Study.Error bars represent 95-percent
confidence intervals.
Figure 3.1-4. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Stephan Lake Complex Focus Area (FA-173) in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP-184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean Number of EPT Taxa Collected0
2
4
6
8
10
Spring
Summer
Fall
Trib Mouth Main ChannelSide Channel
RP- 173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4 Hess RP-173-4 PonarMean Density (Individuals/m2)0
5000
10000
15000
20000
25000
3000045000
50000
Spring
Summer
Fall
Trib Mouth Side SloughMain Channel Side Channel Side Slough
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Figure 3.1-5. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during
three index events for sites within the Stephan Lake Complex Focus Area (FA-173) in the Middle River Segment of the
Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.1-6. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5) from Hess and petite
Ponar grab samples collected in 2013 during three index events for sites within the Stephan Lake Complex Focus Area
(FA-173) in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals.
RP-173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4 Hess RP-173-4 PonarMean Number of Taxa Collected0
10
20
30
40
50
Spring
Summer
Fall
Trib Mouth Side SloughMain Channel Side Channel Side Slough
RP- 173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4 Hess RP-173-4 PonarMean Number of EPT Taxa Collected0
2
4
6
8
10
12
14
Spring
Summer
Fall
Trib Mouth Side SloughMain Channel Side Channel Side Slough
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Figure 3.1-7. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Indian River Focus Area (FA-141) in the Middle River Segment of the Susitna River for
the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.1-8. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Indian River Focus Area (FA-141) in the Middle River Segment of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP-141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4 Hess RP-141-4 PonarMean Density (Individuals/m2)0
5000
10000
15000
20000
25000
40000
50000
Spring
Summer
Fall
Trib Mouth Main Channel Upland SloughSide Channel Upland Slough
RP-141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4 Hess RP-141-4 PonarMean Number of Taxa Collected0
10
20
30
40
Spring
Summer
Fall
Trib Mouth Main Channel Upland SloughSide Channel Upland Slough
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Figure 3.1-9. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Indian River Focus Area (FA-141) in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals.
Figure 3.1-10. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Whiskers Slough Focus Area (FA-104) in the Middle River Segment of the Susitna River
for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP- 141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4 Hess RP-141-4 PonarMean Number of EPT Taxa Collected0
2
4
6
8
10
12
Spring
Summer
Fall
Trib Mouth Main Channel Upland SloughSide Channel Upland Slough
RP-104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 Ponar RP-104-5Mean Density (Individuals/m2)0
4000
8000
12000
16000
20000
40000
Spring
Summer
Fall
Trib Mouth Side Slough Main Channel Upland Slough Side Channel
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Figure 3.1-11. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Whiskers Slough Focus Area (FA-104) in the Middle River Segment of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.1-12. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5) from Hess and petite
Ponar grab samples collected in 2013 during three index events for sites within the Whiskers Slough Focus Area (FA-
104) in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals.
RP-104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 Ponar RP-104-5Mean Number of Taxa Collected0
10
20
30
40
Spring
Summer
Fall
Trib Mouth Side Slough Main Channel Upland Slough Side Channel
RP- 104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 Ponar RP-104-5Mean Number of EPT Taxa Collected0
1
2
3
4
5
6
7
Spring
Summer
Fall
Trib Mouth Side Slough Main Channel Upland Slough Side Channel
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Figure 3.1-13. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Montana Creek area (RP-81) in the Lower River Segment of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.1-14. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Montana Creek area (RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP-81 (Montana Creek)
Station / Site
RP-81-1 Ponar RP-81-2 RP-81-3 RP-81-4Mean Density (Individuals/m2)0
2000
4000
6000
8000
12000
13000
14000
Spring
Summer
Fall
Trib Mouth Main ChannelUpland Slough Side Channel
RP-81 (Montana Creek)
Station / Site
RP-81-1 Ponar RP-81-2 RP-81-3 RP-81-4Mean Number of Taxa Collected0
10
20
30
40
Spring
Summer
Fall
Trib Mouth Main ChannelUpland Slough Side Channel
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Figure 3.1-15. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites within the Montana Creek area (RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals.
RP- 81 (Montana Creek)
Station / Site
RP-81-1 Ponar RP-81-2 RP-81-3 RP-81-4Mean Number of EPT Taxa Collected0
2
4
6
8
10
12
14
Spring
Summer
Fall
Trib Mouth Main ChannelUpland Slough Side Channel
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Figure 3.2-1. Mean drift density estimates from drift samples (n=2) collected in 2013 during three index events for sites within the Watana Dam Focus Area (FA-184) in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.2-2. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5) collected in 2013 during
three index events for sites within the Stephan Lake Complex Focus Area (FA-173) in the Middle River Segment of the
Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals. Bars marked with
a “P” are plankton tows.
RP-184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean Density (Individuals/ft3)0.00
0.05
0.10
0.15
0.20
0.25
0.30
1.00
2.00
3.00
Spring
Summer
Fall
Trib Mouth Main ChannelSide Channel
RP-173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4 TowMean Density (Individuals/ft3)0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
2.0
4.0
6.0
8.0
Spring
Summer
Fall
Trib Mouth Side SloughMain Channel Side Channel
P
P
P
P
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Figure 3.2-3. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5) collected in 2013 during
three index events for sites within the Indian River Focus Area (FA-141) in the Middle River Segment of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals. Bars marked with a “P”
are plankton tows.
Figure 3.2-4. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5) collected in 2013 during
three index events for sites within the Whiskers Slough Focus Area (FA-104) in the Middle River Segment of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals. Bars marked with a “P”
are plankton tows.
RP-141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4 Tow RP-141-5Mean Density (Individuals/ft3)0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.02.03.04.05.0
Spring
Summer
Fall
Trib Mouth Main Channel Upland SloughSide Channel Main Channel
Above Trib
P
P
P
P
RP-104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 Tow RP-104-5Mean Density (Individuals/ft3)0.00
0.05
0.10
0.15
0.20
5.0010.0015.0020.0025.0030.0035.0040.0045.00
Spring
Summer
Fall
Trib Mouth Side Slough Main Channel Upland Slough Side Channel
P
P
P
P
P
P
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Figure 3.2-5. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5) collected in 2013 during
three index events for sites within the Montana Creek area (RP-81) in the Lower River Segment of the Susitna River for
the River Productivity Study. Error bars represent 95-percent confidence intervals. Bars marked with a “P” are
plankton tows.
RP- 81 (Montana Creek)
Station / Site
RP-81-1 RP-81-2 RP-81-3 RP-81-4 RP-81-5Mean Density (Individuals/ft3)0.0
0.1
0.2
0.3
5.0
10.0
15.0
20.0
25.0
Spring
Summer
Fall
Trib Mouth Main ChannelUpland Slough Side Channel Side Channel
Above Trib Mouth
P P
N/A
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Figure 3.3-1. Mean density estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for three sites on the Talkeetna River (TKA) for the River Productivity Study. Error bars represent 95-
percent confidence intervals.
Figure 3.3-2. Mean taxa richness estimates (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for three sites on the Talkeetna River (TKA) for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP-TKA (Talkeetna River)
Station / Site
RP-TKA-1 RP-TKA-2 RP-TKA-3Mean Density (Individuals/m2)0
4000
8000
12000
16000
20000
Spring
Summer
Fall
Side SloughSide Channel Upland Slough
RP-TKA (Talkeetna River)
Station / Site
RP-TKA-1 RP-TKA-2 RP-TKA-3Mean Number of Taxa Collected0
5
10
15
20
25
30
35
Spring
Summer
Fall
Side SloughSide Channel Upland Slough
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Figure 3.3-3. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5) from Hess and petite
Ponar grab samples collected in 2013 during three index events for three sites on the Talkeetna River (TKA) for the
River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.3-4. Mean drift density estimates (individuals/ft3) from drift samples (n=2) and plankton tows (n=5) collected in 2013 during three index events for three sites on the Talkeetna River (TKA) for the River Productivity Study. Error bars
represent 95-percent confidence intervals. Bars marked with a “P” are plankton tows.
RP-TKA (Talkeetna River)
Station / Site
RP-TKA-1 RP-TKA-2 RP-TKA-3Mean Number of EPT Taxa Collected0
2
4
6
8
10
12
14
Spring
Summer
Fall
Side SloughSide Channel Upland Slough
RP-TKA (Talkeetna River)
Station / Site
RP-TKA-1 RP-TKA-2 Tow RP-TKA-3Mean Density (Individuals/ft3)0.00
0.05
0.10
0.15
1.00
2.00
3.00
4.00
Spring
Summer
Fall
Side SloughSide Channel Upland Slough
P P P
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Figure 3.4-1. Monthly length-frequency distributions of juvenile Chinook salmon sampled in the Middle and Lower Susitna River during 2013. Y-axes differ among plots.
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Figure 3.4-2. Monthly length-frequency distributions of juvenile coho salmon sampled in the Middle and Lower Susitna River during 2013. Y-axes differ among plots.
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Figure 3.4-3. Box plots showing the length distribution of Chinook salmon as determined by the scale analysis. No Chinook salmon smaller than 50 mm were aged, so the true length distribution of age-0 fish extends to smaller sizes
than indicated in the figure. Horizontal lines indicate the median value of each group, rectangles indicate the 25th and 75th percentiles, and whiskers and closed circles indicate values outside this range.
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Figure 3.4-4. Box plots showing the length distribution of coho salmon as determined by the scale analysis. No coho salmon smaller than 48 mm were aged, so the true length distribution of age-0 fish extends to smaller sizes than
indicated in the figure. Horizontal lines indicate the median value of each group, rectangles indicate the 25th and 75th percentiles, and whiskers and closed circles indicate values outside this range.
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Figure 3.4-5. Monthly length-frequency distributions of juvenile Chinook salmon sampled at station RP-104, Whiskers Creek and Slough, during 2013. Y-axes differ among plots.
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Figure 3.4-6. Monthly length-frequency distributions of juvenile Chinook salmon sampled at station RP-141, Indian River, during 2013. Y-axes differ among plots.
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Figure 3.4-7. Generalized growth trajectories for age-0, age-1, and age-2 Chinook salmon, developed from empirical
data for bioenergetics model inputs. Separate growth patterns were developed using data from RP-104 (Whiskers
Creek and Slough) and RP-141 (Indian River). The growth rates reported in the Middle Susitna River during 1984 are
shown for comparison.
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Figure 3.4-8. Monthly length-frequency distributions of juvenile coho salmon sampled at station RP-104, Whiskers Creek and Slough, during 2013. Y-axes differ among plots.
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Figure 3.4-9. Monthly length-frequency distributions of juvenile coho salmon sampled at station RP-141, Indian River, during 2013. Y-axes differ among plots.
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Figure 3.4-10. Generalized growth trajectories for age-0 and age-1 coho salmon, developed from empirical data for bioenergetics model inputs. Separate growth patterns were developed using data from RP-104 (Whiskers Creek and
Slough) and RP-141 (Indian River). The growth rates reported in the Middle Susitna River during 1984 are shown for
comparison.
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Figure 3.4-11. Stable isotope δ13C values of all endmember samples collected in 2013 within Focus Areas 81, 104, 141, and 184.
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Figure 3.4-12. Stable isotope δ13C of all algae samples collected in 2013. Data points are stratified by season, macrohabitat type, and Focus Area.
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Figure 3.4-13. Stable isotope δ13C of all benthic organic matter samples collected in 2013. Data points are stratified by season, macrohabitat type, and Focus Area.
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Figure 3.4-14. Stable isotope δ13C of all organic matter drift samples collected in 2013. Data points are stratified by season, macrohabitat type, and Focus Area.
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Figure 3.4-15. Diet proportion estimates from stable isotope mixing model showing seasonal trends in diet composition of juvenile Chinook salmon, juvenile coho salmon, and juvenile and adult rainbow trout sampled between June and
October. Sample sizes for each species – age class collected during each seasonal sampling event are listed above each bar. The “freshwater” source type includes all aquatic macroinvertebrate functional feeding groups, the
“terrestrial” source type includes terrestrial macroinvertebrates, and the “marine” source type includes spawning
salmon carcass and eggs.
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Figure 3.4-16. Diet proportion estimates from stable isotope mixing model showing trends among study reaches in diet
composition of juvenile Chinook salmon, juvenile coho salmon, and juvenile and adult rainbow trout sampled between
June and October. “FA” refers to Focus Area and its associated river mile. Sample sizes for each species – age class
collected during each seasonal sampling event are listed above each bar. The “freshwater” source type includes all
aquatic macroinvertebrate functional feeding groups, the “terrestrial” source type includes terrestrial macroinvertebrates, and the “marine” source type includes spawning salmon carcass and eggs.
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Figure 3.4-17. Diet proportion estimates from stable isotope mixing model showing trends between macrohabitat types in diet composition of juvenile Chinook salmon, juvenile coho salmon, and juvenile and adult rainbow trout sampled
between June and October. Sample sizes for each species – age class collected during each seasonal sampling event
are listed above each bar. The “freshwater” source type includes all aquatic macroinvertebrate functional feeding
groups, the “terrestrial” source type includes terrestrial macroinvertebrates, and the “marine” source type includes
spawning salmon carcass and eggs.
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Figure 3.5-1. Proportion (by dry mass) of fish eggs in the stomach contents of individual fish sampled by gastric
lavage, as a function of fork length. Figure is truncated at 150 mm fork length to show detail at smaller lengths.
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Figure 3.5-2. Proportion (by dry mass) of prey fish in the stomach contents of individual fish sampled by gastric lavage,
as a function of fork length.
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Figure 3.5-3. Seasonal trends in diet composition of juvenile Chinook salmon, juvenile coho salmon, and juvenile and adult rainbow trout sampled between June and October in the Susitna River. Diet proportions (by dry mass) were
determined by stomach content analysis, and the numbers of non-empty samples are shown in parentheses.
Terrestrial invertebrates are broken down by aquatic and terrestrial origin of their larval stage.
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Figure 3.5-4. Large-scale spatial trends in diet composition of juvenile Chinook salmon, juvenile coho salmon, and juvenile and adult rainbow trout sampled at three focus areas Susitna River. Diet proportions (by dry mass) were
determined by stomach content analysis, and the numbers of non-empty samples are shown in parentheses.
Terrestrial invertebrates are broken down by aquatic and terrestrial origin of their larval stage.
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Figure 3.5-5. Small-scale spatial trends in diet composition of juvenile Chinook salmon, juvenile coho salmon, and juvenile and adult rainbow trout sampled in four macrohabitat types in the Susitna River. Diet proportions (by dry
mass) were determined by stomach content analysis, and the numbers of non-empty samples are shown in
parentheses. Terrestrial invertebrates are broken down by aquatic and terrestrial origin of their larval stage.
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Figure 3.6-1. Mean density estimates (n=3) from Hester-Dendy multiplate samplers collected in clear and warm water conditions (HD-1) in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week
colonization period for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.6-2. Mean density estimates (n=3) from Hester-Dendy multiplate samplers collected in clear and cold water conditions (HD-2) in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week
colonization period for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP-104 (Whiskers Slough)
Clear and Warm
Days of Deployment
7 15 28 42 57Mean Density (Individuals/m2)0
2000
4000
6000
8000
12000
14000
Shallow
Deep
RP-104 (Whiskers Slough)
Clear and Cold
Days of Deployment
7 15 28 42 57Mean Density (Individuals/m2)0
1000
2000
3000
4000
5000
6000
Shallow
Deep
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Figure 3.6-3. Mean taxa richness estimates (n=3) from Hester-Dendy multiplate samplers collected in clear and warm water conditions (HD-1) in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week colonization period for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.6-4. Mean taxa richness estimates (n=3) from Hester-Dendy multiplate samplers collected in clear and cold water conditions (HD-2) in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week
colonization period for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP-104 (Whiskers Slough)
Clear and Warm
Days of Deployment
7 15 28 42 57Mean Taxa Richness (No. of Taxa)0
10
20
30
40
50
Shallow
Deep
RP-104 (Whiskers Slough)
Clear and Cold
Days of Deployment
7 15 28 42 57Mean Taxa Richness (No. of Taxa)0
2
4
6
8
10
12
14
16
18
Shallow
Deep
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Figure 3.6-5. Mean density estimates (n=3) from Hester-Dendy multiplate samplers collected in turbid and cold water conditions (HD-3) in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week colonization period for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.6-6. Mean density estimates (n=3) from Hester-Dendy multiplate samplers collected in turbid and warm water conditions (HD-4) in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week
colonization period for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP-104 (Whiskers Slough)
Turbid and Cold
Days of Deployment
8 21 35 49Mean Density (Individuals/m2)0
50
100
150
200
250
300
Shallow
Deep
RP-104 (Whiskers Slough)
Turbid and Warm
Days of Deployment
9 22 36 50Mean Density (Individuals/m2)0
200
400
600
800
1000
1200
Shallow
Deep
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Figure 3.6-7. Mean taxa richness estimates (n=3) from Hester-Dendy multiplate samplers collected in turbid and cold water conditions (HD-3) in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week colonization period for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 3.6-8. Mean taxa richness estimates (n=3) from Hester-Dendy multiplate samplers collected in turbid and warm water conditions (HD-4) in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week
colonization period for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP-104 (Whiskers Slough)
Turbid and Cold
Days of Deployment
8 21 35 49Mean Taxa Richness (No. of Taxa)0
2
4
6
8
10
Shallow
Deep
RP-104 (Whiskers Slough)
Turbid and Warm
Days of Deployment
9 22 36 50Mean Taxa Richness (No. of Taxa)0
2
4
6
8
10
12
14
16
Shallow
Deep
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APPENDIX A. ADDITIONAL TABLES AND FIGURES
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TABLES
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Table A3.1-1. Mean density and taxonomic richness values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Watana Dam Focus area (FA-184) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat
Type
Sampling
Device
Density
(sq m)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Mayfly (E)
Taxa
Avg (Total)
Stonefly
(P) Taxa
Avg (Total)
Caddisfly
(T)Taxa
Avg (Total)
Chironomid
Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-184-1 TM Hess 3284.5 24.6 (44) 5.8 (8) 4.4 (5) 1.4 (3) 0 (0) 14.4 (25) 2.29 0.72
Spr RP-184-2 SC Hess 125.6 5.8 (17) 1.2 (4) 0.4 (2) 0.8 (2) 0 (0) 3.6 (10) 1.42 0.87
Spr RP-184-3 MC Hess 246.5 8.4 (20) 2 (5) 1.2 (3) 0.8 (2) 0 (0) 4.4 (10) 1.84 0.90
Sum RP-184-1 TM Hess 2114.0 25 (49) 5.6 (11) 2.6 (5) 3 (6) 0 (0) 13 (25) 1.97 0.62
Sum RP-184-2 SC Hess 239.5 7.4 (23) 1.2 (4) 0.4 (2) 0.8 (2) 0 (0) 4 (15) 1.46 0.77
Sum RP-184-3 MC Hess 216.3 8.8 (24) 1 (2) 0.2 (1) 0.8 (1) 0 (0) 4.2 (15) 1.80 0.88
Fall RP-184-1 TM Hess 2560.5 19 (38) 7.4 (11) 3.6 (4) 3.6 (6) 0.2 (1) 6.4 (16) 1.70 0.58
Fall RP-184-2 SC Hess 646.5 9.4 (24) 4.6 (8) 1.4 (3) 3.2 (5) 0 (0) 2.8 (11) 1.56 0.75
Fall RP-184-3 MC Hess 193.0 6.6 (15) 3.4 (6) 1 (2) 2.4 (4) 0 (0) 1.6 (6) 1.43 0.81
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Table A3.1-2. Mean taxonomic composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Watana Dam Focus area (FA-184) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat
Type
Sampling Device Percent Mayflies Percent Stoneflies Percent Caddisflies
Percent Chiro-
nomids
Percent Other
Diptera
Percent Other
insects
Percent Non-
insect
EPT:Chiro Ratio
Percent Top
Taxa
Percent Top 3 Taxa
Spr RP-184-1 TM Hess 24.01 9.51 0.00 61.39 1.70 0.00 3.39 0.35 30.72 60.64
Spr RP-184-2 SC Hess 2.79 12.81 0.00 57.02 24.88 0.00 2.50 0.19 43.78 75.71
Spr RP-184-3 MC Hess 6.84 8.14 0.00 55.77 23.45 0.00 5.80 0.21 30.67 67.22
Sum RP-184-1 TM Hess 2.74 50.80 0.00 21.61 9.61 0.00 15.24 0.71 48.44 70.26
Sum RP-184-2 SC Hess 1.72 6.65 0.00 68.13 7.03 0.00 16.47 0.10 52.64 80.00
Sum RP-184-3 MC Hess 0.61 6.47 0.00 43.37 33.41 0.00 16.15 0.12 35.92 69.02
Fall RP-184-1 TM Hess 7.27 36.12 0.13 13.13 40.69 0.00 2.67 0.77 50.17 78.44
Fall RP-184-2 SC Hess 7.90 41.10 0.00 11.71 35.96 0.00 3.33 0.82 43.62 76.97
Fall RP-184-3 MC Hess 7.63 34.26 0.00 9.23 48.37 0.00 0.51 0.86 48.30 79.25
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Table A3.1-3. Mean functional feeding group composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Watana Dam Focus area (FA-184) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat Type
Sampling Device
Percent Collector Gatherers
Percent Collector Filterers
Percent Scrapers Percent Shredders Percent Predators Percent Parasites
Percent Other FFGs
Spr RP-184-1 TM Hess 65.79 1.50 20.02 0.32 12.37 0.00 0.00
Spr RP-184-2 SC Hess 58.27 24.88 1.25 1.54 14.06 0.00 0.00
Spr RP-184-3 MC Hess 61.90 23.45 0.48 0.48 11.56 2.14 0.00
Sum RP-184-1 TM Hess 33.40 7.75 1.95 50.79 4.06 2.04 0.00
Sum RP-184-2 SC Hess 81.38 7.03 1.72 3.54 4.22 2.11 0.00
Sum RP-184-3 MC Hess 44.04 33.41 0.61 0.61 14.61 6.74 0.00
Fall RP-184-1 TM Hess 14.76 40.15 6.24 34.85 3.87 0.13 0.00
Fall RP-184-2 SC Hess 15.32 35.96 5.69 37.04 5.16 0.83 0.00
Fall RP-184-3 MC Hess 14.17 48.37 3.21 30.88 3.38 0.00 0.00
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Table A3.1-4. Mean density and taxonomic richness values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Stephan Lake Complex Focus area (FA-173) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat
Type
Sampling
Device
Density
(sq m)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Mayfly (E)
Taxa
Avg (Total)
Stonefly
(P) Taxa
Avg (Total)
Caddisfly
(T)Taxa
Avg (Total)
Chironomid
Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-173-1 TM Hess 2620.9 26.4 (52) 6 (10) 3.8 (5) 1.6 (3) 0.6 (2) 15.8 (31) 2.56 0.79
Spr RP-173-2 MC Hess 95.3 5.2 (21) 1 (4) 0.4 (2) 0.4 (1) 0.2 (1) 3.4 (15) 1.37 0.75
Spr RP-173-3 SC Hess 1851.2 21.8 (42) 5 (11) 3 (7) 1.6 (3) 0.4 (1) 11.2 (22) 2.26 0.75
Spr RP-173-4 SS P. Ponar 930.0 7.6 (28) 0 (0) 0 (0) 0 (0) 0 (0) 5.2 (19) 1.27 0.73
Spr RP-173-4 SS Hess 11769.5 25.4 (42) 4.4 (8) 3 (5) 1.2 (2) 0.2 (1) 16.2 (28) 2.32 0.72
Sum RP-173-1 TM Hess 1441.2 26.8 (54) 7.6 (15) 3.2 (7) 3.6 (6) 0.8 (2) 11.2 (23) 2.40 0.80
Sum RP-173-2 MC Hess 127.9 5.8 (21) 1.6 (7) 0.4 (2) 1 (4) 0.2 (1) 1.8 (8) 1.42 0.93
Sum RP-173-3 SC Hess 5930.2 25.2 (46) 3.4 (8) 1 (3) 2 (3) 0.4 (2) 16.6 (28) 2.18 0.67
Sum RP-173-4 SS P. Ponar 4520.8 13.4 (25) 0 (0) 0 (0) 0 (0) 0 (0) 10.6 (20) 1.89 0.73
Sum RP-173-4 SS Hess 28720.0 26 (45) 4 (8) 1 (2) 2.2 (3) 0.8 (3) 15.6 (25) 2.40 0.74
Post-Storm RP-173-4 SS P. Ponar 783.6 9.2 (28) 0.2 (1) 0 (0) 0.2 (1) 0 (0) 6.4 (20) 1.94 0.94
Post-Storm RP-173-4 SS Hess 17066.8 18.8 (41) 2.6 (7) 0.4 (2) 2 (4) 0.2 (1) 11.8 (22) 1.75 0.60
Fall RP-173-1 TM Hess 1430.2 18.6 (42) 7.2 (11) 4 (6) 2.6 (3) 0.6 (2) 7.4 (21) 2.10 0.72
Fall RP-173-2 MC Hess 1095.3 12.4 (29) 6 (12) 1.8 (5) 3.8 (5) 0.4 (2) 3 (8) 1.57 0.64
Fall RP-173-3 SC Hess 3211.6 23.6 (50) 5.6 (11) 1.8 (4) 3.4 (5) 0.4 (2) 12 (27) 2.07 0.66
Fall RP-173-4 SS P. Ponar 361.7 4.6 (14) 0.2 (1) 0 (0) 0.2 (1) 0 (0) 4.2 (12) 1.35 0.95
Fall RP-173-4 SS Hess 7391.5 33 (44) 7.5 (10) 2 (3) 4.5 (6) 1 (1) 17.5 (24) 2.31 0.66
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Table A3.1-5. Mean taxonomic composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Stephan Lake Complex Focus area (FA-173) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat
Type
Sampling Device Percent Mayflies Percent Stoneflies Percent Caddisflies
Percent Chiro-
nomids
Percent Other
Diptera
Percent Other
insects
Percent Non-
insect
EPT:Chiro Ratio Percent Top Taxa
Percent Top 3
Taxa
Spr RP-173-1 TM Hess 26.91 3.24 0.69 59.64 2.89 0.00 6.63 0.34 20.64 50.77
Spr RP-173-2 MC Hess 6.50 5.18 1.18 69.91 7.00 0.00 10.24 0.15 43.24 71.32
Spr RP-173-3 SC Hess 3.74 2.06 0.24 52.70 0.26 0.00 41.01 0.10 28.75 60.13
Spr RP-173-4 SS P. Ponar 0.00 0.00 0.00 71.30 5.56 0.00 23.15 0.00 32.80 61.68
Spr RP-173-4 SS Hess 2.21 0.70 0.07 73.31 0.06 0.00 23.64 0.04 26.74 58.80
Sum RP-173-1 TM Hess 8.71 11.82 0.88 42.01 9.46 0.00 27.11 0.29 33.74 56.52
Sum RP-173-2 MC Hess 1.38 19.58 0.69 28.07 4.58 0.00 45.71 0.42 39.08 80.83
Sum RP-173-3 SC Hess 0.79 3.79 0.12 76.44 1.10 0.00 17.77 0.06 36.05 64.86
Sum RP-173-4 SS P. Ponar 0.00 0.00 0.00 62.36 2.28 0.00 35.37 0.00 41.31 66.74
Sum RP-173-4 SS Hess 1.41 2.05 0.26 52.82 17.26 0.00 26.20 0.07 27.34 54.99
Post-
Storm RP-173-4 SS P. Ponar 0.00 1.67 0.00 76.70 3.38 0.00 18.26 0.02 27.51 60.87
Post-
Storm RP-173-4 SS Hess 0.19 2.44 0.06 74.73 0.69 0.00 21.88 0.04 43.37 77.28
Fall RP-173-1 TM Hess 18.21 13.99 0.76 25.49 35.18 0.33 6.04 0.56 36.57 61.48
Fall RP-173-2 MC Hess 6.61 33.40 0.49 8.69 47.26 0.00 3.55 0.84 51.03 77.29
Fall RP-173-3 SC Hess 3.94 44.28 0.24 32.27 5.54 0.00 13.73 0.60 41.84 66.42
Fall RP-173-4 SS P. Ponar 0.00 4.00 0.00 92.92 0.00 0.00 3.08 0.04 38.97 78.82
Fall RP-173-4 SS Hess 1.19 9.80 1.34 76.24 6.39 0.00 5.05 0.14 39.40 59.85
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.1-6. Mean functional feeding group composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Stephan Lake Complex Focus area (FA-173) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat Type
Sampling Device
Percent Collector Gatherers
Percent Collector Filterers
Percent Scrapers Percent Shredders Percent Predators Percent Parasites
Percent Other FFGs
Spr RP-173-1 TM Hess 76.90 2.37 13.62 2.34 4.52 0.21 0.05
Spr RP-173-2 MC Hess 73.29 10.68 2.50 10.35 1.18 0.00 2.00
Spr RP-173-3 SC Hess 63.16 0.65 0.83 1.70 15.56 18.11 0.00
Spr RP-173-4 SS P. Ponar 50.00 4.63 21.30 8.33 2.78 12.96 0.00
Spr RP-173-4 SS Hess 82.00 0.00 0.86 4.02 5.38 6.17 1.57
Sum RP-173-1 TM Hess 64.28 5.58 5.89 15.03 4.45 2.56 2.20
Sum RP-173-2 MC Hess 50.21 2.76 0.69 6.38 17.77 12.81 9.38
Sum RP-173-3 SC Hess 76.62 1.42 3.52 4.08 4.42 9.64 0.29
Sum RP-173-4 SS P. Ponar 30.38 4.16 21.32 10.97 0.00 33.00 0.18
Sum RP-173-4 SS Hess 65.88 17.23 0.89 4.39 5.51 5.60 0.50
Post-
Storm RP-173-4 SS P. Ponar 51.92 1.21 22.51 3.77 2.62 12.98 5.00
Post-
Storm RP-173-4 SS Hess 64.79 0.71 0.77 27.13 2.98 3.55 0.06
Fall RP-173-1 TM Hess 30.17 36.13 6.04 24.81 2.26 0.30 0.29
Fall RP-173-2 MC Hess 9.39 46.80 4.33 31.43 7.80 0.26 0.00
Fall RP-173-3 SC Hess 36.10 5.57 0.82 46.98 10.23 0.21 0.08
Fall RP-173-4 SS P. Ponar 38.97 1.54 34.97 17.44 4.00 3.08 0.00
Fall RP-173-4 SS Hess 64.80 6.39 1.34 10.63 16.25 0.45 0.15
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 7 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.1-7. Mean density and taxonomic richness values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Indian River Focus area (FA-141) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat
Type
Sampling
Device
Density
(sq m)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Mayfly (E)
Taxa
Avg (Total)
Stonefly
(P) Taxa
Avg (Total)
Caddisfly
(T)Taxa
Avg (Total)
Chironomid
Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-141-1 TM Hess 1402.3 14.6 (31) 5 (9) 3.4 (5) 1.4 (3) 0.2 (1) 6.6 (15) 1.91 0.72
Spr RP-141-2 SC Hess 346.5 14 (37) 4.4 (11) 2.2 (4) 1.4 (4) 0.8 (3) 6.8 (19) 2.33 0.94
Spr RP-141-3 MC Hess 83.7 4 (12) 0.4 (2) 0.2 (1) 0.2 (1) 0 (0) 3.2 (8) 1.19 0.90
Spr RP-141-4 US Hess 19438.1 14.4 (26) 1.6 (3) 0.4 (1) 0.2 (1) 1 (1) 8.8 (18) 1.86 0.70
Spr RP-141-4 US P. Ponar 8645.0 18 (44) 0.4 (2) 0.4 (2) 0 (0) 0 (0) 13 (31) 1.94 0.67
Sum RP-141-1 TM Hess 4705.4 28.2 (51) 8.2 (14) 4.2 (6) 3.2 (5) 0.8 (3) 13.2 (22) 1.87 0.56
Sum RP-141-2 SC Hess 972.1 14.4 (38) 4.6 (11) 1.8 (5) 2.6 (5) 0.2 (1) 6.2 (17) 1.92 0.73
Sum RP-141-3 MC Hess 134.9 7.2 (21) 3.8 (12) 1.8 (6) 1.8 (5) 0.2 (1) 2.2 (5) 1.78 0.92
Sum RP-141-4 US Hess 19040.3 13.5 (23) 0.75 (2) 0 (0) 0.5 (1) 0.25 (1) 9 (16) 1.55 0.60
Sum RP-141-4 US P. Ponar 9261.9 10.4 (24) 0 (0) 0 (0) 0 (0) 0 (0) 5.8 (15) 1.37 0.61
Fall RP-141-1 TM Hess 1297.7 17.6 (39) 8.4 (14) 4.4 (6) 2.8 (5) 1.2 (3) 4.8 (13) 1.92 0.68
Fall RP-141-2 SC P. Ponar 1162.5 5.6 (17) 0.6 (2) 0 (0) 0.4 (1) 0.2 (1) 5 (15) 0.96 0.64
Fall RP-141-3 MC Hess 69.8 3.8 (15) 0.6 (3) 0.4 (2) 0.2 (1) 0 (0) 2 (8) 1.08 0.74
Fall RP-141-4 US Hess 2065.9 19 (30) 3.33 (7) 1 (2) 1.67 (3) 0.667 (2) 11 (16) 2.20 0.75
Fall RP-141-4 US P. Ponar 3108.6 8.4 (16) 0 (0) 0 (0) 0 (0) 0 (0) 5.2 (10) 1.50 0.73
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.1-8. Mean taxonomic composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Indian River Focus area (FA-141) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat
Type
Sampling Device Percent Mayflies Percent Stoneflies Percent Caddisflies
Percent Chiro-
nomids
Percent Other
Diptera
Percent Other
insects
Percent Non-
insect
EPT:Chiro Ratio Percent Top Taxa
Percent Top 3
Taxa
Spr RP-141-1 TM Hess 48.88 24.45 0.14 20.98 2.64 0.00 2.92 0.78 29.73 70.02
Spr RP-141-2 SC Hess 17.19 6.79 2.98 41.80 18.68 0.00 12.56 0.36 20.03 46.71
Spr RP-141-3 MC Hess 6.67 3.33 0.00 85.49 4.51 0.00 0.00 0.11 47.25 89.80
Spr RP-141-4 US Hess 0.33 0.09 1.33 72.86 0.33 0.00 25.07 0.03 39.47 67.39
Spr RP-141-4 US P. Ponar 0.30 0.00 0.00 43.63 0.98 0.00 55.09 0.01 44.54 68.61
Sum RP-141-1 TM Hess 10.38 21.86 0.34 60.52 1.40 0.00 5.50 0.35 50.54 71.92
Sum RP-141-2 SC Hess 5.27 15.61 0.26 60.44 3.97 0.00 14.45 0.27 41.69 65.58
Sum RP-141-3 MC Hess 20.20 27.33 2.22 36.72 8.85 0.00 4.68 0.57 31.37 62.24
Sum RP-141-4 US Hess 0.00 0.13 0.36 91.26 0.48 0.00 7.77 0.01 40.93 84.30
Sum RP-141-4 US P. Ponar 0.00 0.00 0.00 36.07 1.97 0.00 61.97 0.00 50.94 82.49
Fall RP-141-1 TM Hess 20.14 56.71 1.66 9.92 6.22 0.00 5.36 0.89 47.01 64.64
Fall RP-141-2 SC P. Ponar 0.00 1.20 1.43 97.37 0.00 0.00 0.00 0.03 67.43 93.49
Fall RP-141-3 MC Hess 6.67 3.33 0.00 70.00 13.33 0.00 6.67 0.23 29.58 67.50
Fall RP-141-4 US Hess 0.82 1.66 0.55 74.84 0.38 1.32 20.41 0.04 29.03 61.35
Fall RP-141-4 US P. Ponar 0.00 0.00 0.00 40.68 0.44 0.00 58.87 0.00 46.45 81.02
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 9 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.1-9. Mean functional feeding group composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Indian River Focus area (FA-141) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat Type
Sampling Device
Percent Collector Gatherers
Percent Collector Filterers
Percent Scrapers Percent Shredders Percent Predators Percent Parasites
Percent Other FFGs
Spr RP-141-1 TM Hess 33.60 1.76 36.19 0.99 27.46 0.00 0.00
Spr RP-141-2 SC Hess 55.61 10.62 5.75 10.12 15.51 0.00 2.38
Spr RP-141-3 MC Hess 82.16 3.33 7.84 3.33 3.33 0.00 0.00
Spr RP-141-4 US Hess 75.99 0.00 17.67 1.59 0.50 4.24 0.00
Spr RP-141-4 US P. Ponar 47.68 6.12 1.83 0.89 10.31 32.17 1.01
Sum RP-141-1 TM Hess 62.39 0.50 9.72 15.48 11.91 0.00 0.00
Sum RP-141-2 SC Hess 65.80 0.26 1.65 23.06 8.01 1.22 0.00
Sum RP-141-3 MC Hess 43.26 8.21 10.81 24.83 10.03 2.86 0.00
Sum RP-141-4 US Hess 82.61 0.00 14.39 0.79 0.61 1.60 0.00
Sum RP-141-4 US P. Ponar 25.49 12.76 0.00 0.07 21.28 39.52 0.88
Fall RP-141-1 TM Hess 18.27 6.23 13.45 52.55 9.50 0.00 0.00
Fall RP-141-2 SC P. Ponar 26.66 2.03 0.33 70.07 0.91 0.00 0.00
Fall RP-141-3 MC Hess 70.00 13.33 3.33 6.67 6.67 0.00 0.00
Fall RP-141-4 US Hess 87.69 0.38 3.21 3.44 0.90 1.11 3.28
Fall RP-141-4 US P. Ponar 50.72 6.62 0.00 4.42 21.37 16.87 0.00
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 10 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.1-10. Mean density and taxonomic richness values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Whiskers Slough Focus area (FA-104) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat
Type
Sampling Device Density (sq m)
Taxa Richness
Avg (Total)
EPT Richness
Avg (Total)
Mayfly (E) Taxa
Avg (Total)
Stonefly (P) Taxa
Avg (Total)
Caddisfly (T)Taxa
Avg (Total)
Chironomid Taxa
Avg (Total)
Diversity (H') Evenness (J')
Spr RP-104-1 TM Hess 1662.8 24 (53) 3.4 (9) 1.8 (4) 0.6 (2) 1 (3) 14.2 (29) 2.39 0.78
Spr RP-104-2 SS Hess 379.1 12.4 (30) 3 (6) 2 (4) 1 (2) 0 (0) 6.4 (15) 2.13 0.89
Spr RP-104-3 MC Hess 220.9 7.4 (16) 0.2 (1) 0 (0) 0.2 (1) 0 (0) 5.4 (10) 1.55 0.81
Spr RP-104-4 US P. Ponar 1420.8 9.6 (32) 0.2 (1) 0 (0) 0 (0) 0.2 (1) 5.8 (19) 1.74 0.87
Spr RP-104-5 SC Hess 176.7 7.8 (22) 1.2 (5) 0.6 (3) 0.6 (2) 0 (0) 5 (13) 1.70 0.90
Sum RP-104-1 TM Hess 5696.1 27.2 (53) 1.4 (6) 0.4 (2) 0.4 (2) 0.6 (2) 18.2 (31) 2.20 0.67
Sum RP-104-2 SS Hess 21695.3 26.2 (61) 4 (11) 1.2 (3) 1.2 (4) 1.6 (4) 16.2 (33) 2.42 0.74
Sum RP-104-3 MC Hess 109.3 4.6 (17) 0.4 (2) 0.2 (1) 0.2 (1) 0 (0) 2.6 (8) 1.14 0.68
Sum RP-104-4 US P.Ponar 7267.8 18.2 (40) 0 (0) 0 (0) 0 (0) 0 (0) 14.4 (30) 2.05 0.74
Sum RP-104-5 SC Hess 41.9 2.6 (8) 1.2 (4) 0.6 (2) 0.6 (2) 0 (0) 0.4 (2) 0.78 0.74
Post-Storm RP-104-2 SS Hess 3246.5 26.6 (52) 2.4 (5) 0.6 (1) 1.6 (3) 0.2 (1) 17.6 (34) 2.05 0.63
Fall RP-104-1 TM Hess 8915.8 26.6 (47) 4.6 (10) 1 (3) 1.4 (3) 2.2 (4) 16.4 (24) 2.19 0.67
Fall RP-104-2 SS P.Ponar 3134.5 13.4 (30) 0 (0) 0 (0) 0 (0) 0 (0) 10.2 (25) 1.83 0.72
Fall RP-104-2 SS Hess 13200.0 38 (48) 5.5 (8) 1.5 (2) 2 (3) 2 (3) 25.5 (30) 2.59 0.71
Fall RP-104-3 MC Hess 111.6 5.8 (17) 1 (3) 0.2 (1) 0.8 (2) 0 (0) 3.8 (11) 1.61 0.92
Fall RP-104-4 US P. Ponar 12384.5 21.4 (37) 0 (0) 0 (0) 0 (0) 0 (0) 16 (27) 1.67 0.55
Fall RP-104-5 SC Hess 172.1 6.6 (17) 2.4 (6) 0.2 (1) 2 (4) 0.2 (1) 3 (8) 1.56 0.83
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 11 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.1-11. Mean taxonomic composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Whiskers Slough Focus area (FA-104) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat Type
Sampling Device Percent Mayflies Percent Stoneflies Percent Caddisflies
Percent Chiro-nomids
Percent Other Diptera
Percent Other insects
Percent Non-insect
EPT:Chiro Ratio Percent Top Taxa
Percent Top 3 Taxa
Spr RP-104-1 TM Hess 12.05 0.58 3.05 49.48 3.44 0.00 31.41 0.24 31.82 55.08
Spr RP-104-2 SS Hess 14.75 5.13 0.00 48.48 22.34 0.34 8.95 0.25 29.57 52.40
Spr RP-104-3 MC Hess 0.00 2.00 0.00 74.22 21.21 0.00 2.57 0.03 44.33 76.59
Spr RP-104-4 US P. Ponar 0.00 0.00 1.38 45.96 9.54 0.00 43.12 0.03 37.82 68.58
Spr RP-104-5 SC Hess 3.00 4.50 0.00 70.00 22.50 0.00 0.00 0.09 38.33 66.89
Sum RP-104-1 TM Hess 0.13 0.10 0.20 83.82 2.48 0.00 13.27 0.01 43.62 60.42
Sum RP-104-2 SS Hess 3.69 0.72 1.49 72.39 0.73 0.48 20.49 0.07 28.21 56.01
Sum RP-104-3 MC Hess 2.13 4.26 0.00 68.09 12.77 0.00 12.77 0.04 37.84 62.88
Sum RP-104-4 US P.Ponar 0.00 0.00 0.00 61.06 1.59 0.00 37.34 0.00 36.92 64.21
Sum RP-104-5 SC Hess 15.00 26.67 0.00 25.00 8.33 0.00 25.00 0.73 60.00 91.67
Post-
Storm RP-104-2 SS Hess 0.57 2.74 0.25 45.19 1.10 0.00 50.15 0.07 46.47 68.46
Fall RP-104-1 TM Hess 0.61 2.64 1.86 89.87 0.71 0.00 4.32 0.05 41.58 62.07
Fall RP-104-2 SS P.Ponar 0.00 0.00 0.00 65.68 4.57 0.00 29.75 0.00 39.03 67.64
Fall RP-104-2 SS Hess 1.75 1.55 1.28 72.03 1.90 0.00 21.50 0.06 30.27 54.57
Fall RP-104-3 MC Hess 5.71 10.56 0.00 65.16 16.07 0.00 2.50 0.22 36.79 66.63
Fall RP-104-4 US P. Ponar 0.00 0.00 0.00 60.06 6.21 0.00 33.73 0.00 55.81 77.48
Fall RP-104-5 SC Hess 1.33 48.33 3.00 31.67 0.00 0.00 15.67 0.61 43.00 73.78
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 12 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.1-12. Mean functional feeding group composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events for sites (Spr= Spring, Sum=Summer, Fall) within the Whiskers Slough Focus area (FA-104) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat Type
Sampling Device
Percent Collector Gatherers
Percent Collector Filterers
Percent Scrapers Percent Shredders Percent Predators Percent Parasites
Percent Other FFGs
Spr RP-104-1 TM Hess 73.76 12.49 1.74 4.37 6.29 0.00 1.34
Spr RP-104-2 SS Hess 54.21 20.17 11.02 5.25 9.01 0.34 0.00
Spr RP-104-3 MC Hess 76.79 19.35 0.00 0.57 3.29 0.00 0.00
Spr RP-104-4 US P. Ponar 54.01 17.51 0.00 6.76 5.78 4.13 11.82
Spr RP-104-5 SC Hess 71.67 18.83 2.83 1.33 5.33 0.00 0.00
Sum RP-104-1 TM Hess 53.73 4.39 0.36 5.86 10.91 3.02 21.73
Sum RP-104-2 SS Hess 78.08 3.45 3.11 4.48 6.93 0.05 3.88
Sum RP-104-3 MC Hess 32.45 2.13 0.00 44.15 21.28 0.00 0.00
Sum RP-104-4 US P.Ponar 70.27 7.73 10.15 0.21 6.47 0.75 4.42
Sum RP-104-5 SC Hess 61.67 0.00 3.33 0.00 31.67 0.00 3.33
Post-
Storm RP-104-2 SS Hess 88.99 1.48 0.99 4.65 3.41 0.12 0.36
Fall RP-104-1 TM Hess 65.67 18.48 1.36 8.12 4.99 0.06 1.31
Fall RP-104-2 SS P.Ponar 79.10 2.24 0.00 8.78 2.02 1.24 6.62
Fall RP-104-2 SS Hess 75.91 10.98 1.02 4.62 7.48 0.00 0.00
Fall RP-104-3 MC Hess 61.19 13.57 6.83 18.41 0.00 0.00 0.00
Fall RP-104-4 US P. Ponar 58.74 36.58 1.14 0.30 3.07 0.12 0.05
Fall RP-104-5 SC Hess 28.78 2.33 1.33 60.89 6.67 0.00 0.00
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 13 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.1-13. Mean density and taxonomic richness values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Montana Creek area (RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat
Type
Sampling
Device
Density
(sq m)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Mayfly (E)
Taxa
Avg (Total)
Stonefly
(P) Taxa
Avg (Total)
Caddisfly
(T)Taxa
Avg (Total)
Chironomid
Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-81-1 US P. Ponar 4107.5 13.6 (36) 0.2 (1) 0.2 (1) 0 (0) 0 (0) 9.6 (28) 1.76 0.70
Spr RP-81-2 TM Hess 7579.1 21.2 (42) 6 (11) 4 (7) 1.4 (2) 0.6 (2) 11 (22) 1.73 0.58
Spr RP-81-3 MC Hess 153.5 4.4 (14) 0.4 (2) 0.2 (1) 0.2 (1) 0 (0) 2.6 (7) 0.98 0.71
Spr RP-81-4 SC Hess 123.3 7.8 (24) 1.4 (5) 0.6 (3) 0.8 (2) 0 (0) 4.2 (12) 1.90 0.95
Sum RP-81-1 US P. Ponar 6412.4 9 (16) 0.2 (1) 0 (0) 0 (0) 0.2 (1) 5.6 (10) 1.58 0.73
Sum RP-81-2 TM Hess 3014.0 31.6 (61) 10.2 (20) 5.4 (10) 3.8 (6) 1 (4) 14.8 (28) 2.59 0.75
Sum RP-81-3 MC Hess 7.0 0.6 (3) 0 (0) 0 (0) 0 (0) 0 (0) 0.4 (2) 0.14 0.20
Sum RP-81-4 SC Hess 114.0 6.4 (19) 3.2 (10) 1.8 (5) 1.4 (5) 0 (0) 2 (5) 1.72 0.95
Fall RP-81-1 US Hess 1074.4 17 (42) 0.8 (4) 0.4 (2) 0 (0) 0.4 (2) 10.6 (27) 2.19 0.79
Fall RP-81-2 TM Hess 1397.7 26.8 (53) 8.6 (14) 3.2 (5) 4.2 (5) 1.2 (4) 12.8 (28) 2.63 0.81
Fall RP-81-3 MC Hess 174.4 6 (13) 3.4 (7) 1.6 (4) 1.8 (3) 0 (0) 1.6 (5) 1.41 0.72
Fall RP-81-4 SC Hess 616.3 9.6 (18) 7.4 (11) 2.8 (5) 4 (5) 0.6 (1) 1 (4) 1.71 0.77
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 14 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.1-14. Mean taxonomic composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Montana Creek area (RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat
Type
Sampling Device Percent Mayflies Percent Stoneflies Percent Caddisflies
Percent Chiro-
nomids
Percent Other
Diptera
Percent Other
insects
Percent Non-
insect
EPT:Chiro Ratio Percent Top Taxa
Percent Top 3
Taxa
Spr RP-81-1 US P. Ponar 0.31 0.00 0.00 52.79 1.55 0.00 45.35 0.00 46.15 72.95
Spr RP-81-2 TM Hess 4.98 3.10 0.17 86.54 3.28 0.00 1.93 0.09 47.55 76.91
Spr RP-81-3 MC Hess 4.00 1.43 0.00 58.86 33.33 0.00 2.38 0.07 66.71 90.48
Spr RP-81-4 SC Hess 12.32 9.52 0.00 48.22 23.64 0.00 6.30 0.28 28.76 56.92
Sum RP-81-1 US P. Ponar 0.00 0.00 0.31 42.56 0.22 0.00 56.91 0.01 40.54 80.70
Sum RP-81-2 TM Hess 12.33 6.43 0.47 72.03 5.63 0.00 3.11 0.21 27.37 51.06
Sum RP-81-3 MC Hess 0.00 0.00 0.00 66.67 0.00 0.00 33.33 0.00 30.00 40.00
Sum RP-81-4 SC Hess 24.15 26.87 0.00 31.95 7.08 0.00 9.95 0.61 27.08 64.56
Fall RP-81-1 US Hess 0.51 0.00 0.38 43.37 2.08 0.00 53.67 0.02 29.42 58.03
Fall RP-81-2 TM Hess 9.54 27.72 1.30 45.29 12.72 0.00 3.43 0.46 25.00 50.31
Fall RP-81-3 MC Hess 13.90 21.93 0.00 20.39 43.78 0.00 0.00 0.52 47.05 73.19
Fall RP-81-4 SC Hess 17.77 71.74 1.41 4.66 3.93 0.00 0.48 0.95 39.68 73.57
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 15 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.1-15. Mean functional feeding group composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Montana Creek area (RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat Type
Sampling Device
Percent Collector Gatherers
Percent Collector Filterers
Percent Scrapers Percent Shredders Percent Predators Percent Parasites
Percent Other FFGs
Spr RP-81-1 US P. Ponar 61.23 9.72 0.33 2.14 2.78 22.96 0.84
Spr RP-81-2 TM Hess 88.23 3.60 2.04 0.36 5.78 0.00 0.00
Spr RP-81-3 MC Hess 65.95 30.71 0.95 0.00 2.38 0.00 0.00
Spr RP-81-4 SC Hess 48.77 12.56 10.50 11.76 16.41 0.00 0.00
Sum RP-81-1 US P. Ponar 51.48 28.78 1.18 0.31 5.41 12.85 0.00
Sum RP-81-2 TM Hess 69.78 6.33 9.88 6.72 5.55 0.30 1.44
Sum RP-81-3 MC Hess 66.67 0.00 0.00 33.33 0.00 0.00 0.00
Sum RP-81-4 SC Hess 31.69 7.08 17.28 18.00 25.95 0.00 0.00
Fall RP-81-1 US Hess 54.77 10.57 3.46 11.65 9.08 10.22 0.25
Fall RP-81-2 TM Hess 47.09 8.58 3.72 27.46 12.43 0.20 0.52
Fall RP-81-3 MC Hess 24.78 43.78 7.51 12.84 11.09 0.00 0.00
Fall RP-81-4 SC Hess 16.92 3.46 3.61 56.71 19.31 0.00 0.00
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 16 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.2-1. Mean drift density and taxonomic richness values from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Watana Dam Focus area (FA-184) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat Type
Sampling
Device
Drift
Density
(#/ft3)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Chironomid
Taxa
Avg (Total)
Zooplankton
Taxa
Avg (Total)
Other Non-
Insect
(T)Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-184-1 TM Drift 0.222 37 (53) 6 (9) 15.5 (20) 0 5 (7) 1.99 0.55
Spr RP-184-2 SC Drift 0.075 23.5 (34) 2 (4) 15.5 (21) 0 4.5 (7) 2.05 0.65
Spr RP-184-3 MC Drift 0.052 20 (28) 2.5 (5) 9.5 (13) 0 5.5 (7) 1.94 0.65
Sum RP-184-1 TM Drift 0.125 41.5 (62) 5.5 (10) 23 (33) 0 5.5 (7) 2.71 0.73
Sum RP-184-2 SC Drift 0.007 8 (13) 1 (2) 3 (6) 0 2.5 (3) 1.92 0.93
Sum RP-184-3 MC Drift 0.041 7 (12) 0.5 (1) 5 (8) 0 1 (2) 1.77 0.91
Fall RP-184-1 TM Drift 1.250 12.5 (20) 3.5 (5) 4 (7) 0 3 (5) 0.92 0.35
Fall RP-184-2 SC Drift 0.081 27.5 (40) 4.5 (7) 10.5 (17) 0 10 (13) 2.42 0.73
Fall RP-184-3 MC Drift 0.268 26.5 (36) 5 (6) 10 (17) 0 8 (9) 2.00 0.61
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 17 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.2-2. Mean taxonomic composition metric values (n=5) from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Watana Dam Focus area (FA-184) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat Type
Sampling
Device
Percent
Mayflies
Percent
Stoneflies
Percent
Caddisflies
Percent Chiro-nomids
Percent Other Diptera
Percent Other insects
Percent Zoo-plankton
Percent Other
Non-insects
EPT:Chiro
Ratio
Percent Top 3 Taxa
Spr RP-184-1 TM Drift 5.85 0.81 0.00 80.22 6.10 2.70 0 4.32 0.08 67.28
Spr RP-184-2 SC Drift 2.04 0.43 0.00 63.85 29.16 0.32 0 4.20 0.04 72.73
Spr RP-184-3 MC Drift 0.84 0.94 0.35 47.54 33.11 0.59 0.35 16.28 0.04 73.74
Sum RP-184-1 TM Drift 0.88 3.11 1.13 72.91 6.86 4.84 0 10.27 0.07 52.57
Sum RP-184-2 SC Drift 0.00 5.56 2.08 42.64 15.00 0.00 0 34.72 0.16 59.44
Sum RP-184-3 MC Drift 0.00 3.85 0.00 73.85 9.62 0.00 0 12.69 0.06 61.92
Fall RP-184-1 TM Drift 4.17 0.88 0.86 16.66 76.12 0.30 0 1.02 0.30 88.22
Fall RP-184-2 SC Drift 1.32 4.50 0.51 10.19 26.14 0.00 35.11 22.24 0.38 57.62
Fall RP-184-3 MC Drift 0.74 3.17 0.00 5.94 23.83 0.00 34.38 31.94 0.40 72.05
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 18 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.2-3. Mean drift density and taxonomic richness values from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Stephan Lake Complex Focus area (FA-173) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat Type
Sampling
Device
Drift
Density
(#/ft3)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Chironomid
Taxa
Avg (Total)
Zooplankton
Taxa
Avg (Total)
Other Non-
Insect
(T)Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-173-1 TM Drift 0.084 51.5 (64) 5.5 (7) 23.5 (27) 0 10 (14) 3.16 0.80
Spr RP-173-2 MC Drift 0.154 26.5 (37) 3.5 (4) 13.5 (20) 0 5.5 (6) 2.74 0.84
Spr RP-173-3 SC Drift 0.080 30.5 (41) 3.5 (4) 11 (13) 0 5.5 (8) 2.64 0.77
Spr RP-173-4 SS Plankton Net 0.427 2.4 (6) 0.4 (1) 1.6 (4) 0.4 (1) 0 0.76 0.73
Sum RP-173-1 TM Drift 0.144 38 (52) 9 (13) 16.5 (23) 0 6 (8) 3.17 0.88
Sum RP-173-2 MC Drift 0.188 20.5 (35) 3 (5) 8 (14) 0 3.5 (6) 2.66 0.88
Sum RP-173-3 SC Drift 0.037 3 (5) 0.5 (1) 2.5 (4) 0 0 0.96 0.94
Sum RP-173-4 SS Plankton Net 4.254 8.8 (22) 0 4.4 (12) 2.4 (6) 1 (2) 1.37 0.65
Fall RP-173-1 TM Drift 0.184 30.5 (40) 7.5 (9) 7 (9) 0 8 (11) 2.00 0.59
Fall RP-173-2 MC Drift 0.153 27.5 (39) 6.5 (9) 7.5 (11) 0 10 (13) 2.10 0.64
Fall RP-173-3 SC Plankton Net 0.931 3.2 (9) 0.2 (1) 1.8 (4) 0.6 (2) 0.6 (2) 1.17 0.93
Fall RP-173-4 SS Plankton Net 0.493 1.8 (7) 0 1.4 (5) 0 0.4 (2) 0.60 0.69
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 19 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.2-4. Mean taxonomic composition metric values (n=5) from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Stephan Lake Complex Focus area (FA-173) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat Type
Sampling
Device
Percent
Mayflies
Percent
Stoneflies
Percent
Caddisflies
Percent Chiro-nomids
Percent Other Diptera
Percent Other insects
Percent Zoo-plankton
Percent Other
Non-insects
EPT:Chiro
Ratio
Percent Top 3 Taxa
Spr RP-173-1 TM Drift 4.38 0.69 0.11 34.29 20.10 14.79 0.46 25.18 0.13 38.27
Spr RP-173-2 MC Drift 2.24 2.68 0.00 55.43 19.36 2.68 4.89 12.72 0.08 48.19
Spr RP-173-3 SC Drift 9.59 0.44 0.63 58.93 6.71 12.10 2.94 8.66 0.15 48.18
Spr RP-173-4 SS Plankton
Net 4.41 0.00 0.00 83.79 0.00 0.00 11.80 0 0.03 79.09
Sum RP-173-1 TM Drift 2.72 7.58 1.56 55.49 11.03 7.51 0 14.11 0.18 32.65
Sum RP-173-2 MC Drift 0.88 4.67 1.16 47.23 13.14 21.56 0 11.36 0.12 44.98
Sum RP-173-3 SC Drift 0.00 0.00 10.00 90.00 0.00 0.00 0 0 0.10 95.00
Sum RP-173-4 SS Plankton
Net 0.00 0.00 0.00 81.37 0.77 0.00 13.25 4.60 0.00 78.79
Fall RP-173-1 TM Drift 9.93 5.33 0.64 23.70 50.98 1.13 0.32 7.97 0.38 71.73
Fall RP-173-2 MC Drift 1.41 5.84 1.58 5.06 36.51 0.32 30.39 18.89 0.61 66.24
Fall RP-173-3 SC Plankton
Net 0.00 4.36 0.00 69.12 0.00 0.00 13.42 13.09 0.02 67.38
Fall RP-173-4 SS Plankton
Net 0.00 0.00 0.00 87.08 0.00 0.00 0 12.92 0.00 78.18
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 20 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.2-5. Mean drift density and taxonomic richness values from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Indian River Focus area (FA-141) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat
Type
Sampling
Device
Drift
Density
(#/ft3)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Chironomid
Taxa
Avg (Total)
Zooplankton
Taxa
Avg (Total)
Other Non-
Insect
(T)Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-141-1 TM Drift 0.653 41.5 (56) 7.5 (9) 17.5 (22) 0 7 (10) 3.00 0.81
Spr RP-141-2 SC Drift 0.195 47 (68) 4 (7) 21 (32) 0 10.5 (13) 2.89 0.75
Spr RP-141-3 MC Drift 0.018 10 (18) 0 7 (13) 0 1.5 (3) 1.62 0.91
Spr RP-141-4 US Plankton Net 2.638 9.2 (27) 0.6 (2) 2.6 (11) 3.6 (7) 2 (5) 1.62 0.75
Sum RP-141-1 TM Drift 0.309 40.5 (53) 11.5 (13) 16.5 (19) 0 6.5 (10) 2.60 0.70
Sum RP-141-2 SC Drift 0.011 19.5 (29) 5 (6) 5.5 (9) 0 5.5 (8) 2.54 0.86
Sum RP-141-3 MC Drift 0.042 13.5 (23) 3.5 (6) 5 (8) 0 1.5 (3) 2.23 0.96
Sum RP-141-4 US Plankton Net 0.783 3 (10) 0 1 (4) 0.2 (1) 1.8 (5) 1.03 0.82
Sum RP-141-5 MC, Above
TM Drift 0.013 11.5 (21) 2.5 (4) 3.5 (7) 0 2 (3) 1.46 0.62
Fall RP-141-1 TM Drift 0.471 41 (55) 9.5 (11) 15 (21) 0 7 (9) 2.12 0.57
Fall RP-141-2 SC Plankton Net 0.038 0.6 (3) 0.2 (1) 0.2 (1) 0 0 0.35 0.50
Fall RP-141-3 MC Drift 0.025 21.5 (31) 3 (5) 8 (13) 0 7.5 (9) 2.08 0.68
Fall RP-141-4 US Plankton Net 0.393 4 (16) 0.2 (1) 1.2 (5) 1.2 (5) 1.2 (4) 1.19 0.96
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 21 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.2-6. Mean taxonomic composition metric values (n=5) from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Indian River Focus area (FA-141) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat Type
Sampling
Device
Percent
Mayflies
Percent
Stoneflies
Percent
Caddisflies
Percent Chiro-nomids
Percent Other Diptera
Percent Other insects
Percent Zoo-plankton
Percent Other
Non-insects
EPT:Chiro
Ratio
Percent Top 3 Taxa
Spr RP-141-1 TM Drift 24.11 8.04 1.74 43.52 6.81 7.98 0.14 7.66 0.44 36.55
Spr RP-141-2 SC Drift 4.58 1.46 0.17 44.56 29.84 3.68 7.65 8.05 0.12 48.75
Spr RP-141-3 MC Drift 0.00 0.00 0.00 71.14 25.20 0.00 1.22 2.44 0.00 71.43
Spr RP-141-4 US Plankton Net 0.58 0.00 0.89 24.14 1.89 0.00 53.15 19.36 0.19 73.57
Sum RP-141-1 TM Drift 5.04 10.31 5.59 63.80 5.51 0.78 0 8.98 0.25 55.83
Sum RP-141-2 SC Drift 5.07 14.56 0.00 36.31 13.33 2.34 0 28.39 0.35 46.05
Sum RP-141-3 MC Drift 13.66 7.32 0.00 37.85 21.42 3.66 0 16.10 0.36 49.07
Sum RP-141-4 US Plankton Net 0.00 0.00 0.00 76.60 0.00 0.00 6.20 17.20 0.00 75.87
Sum RP-141-5
MC,
Above
TM
Drift 0.98 6.67 62.84 9.51 2.94 9.80 0 7.25 0.86 78.04
Fall RP-141-1 TM Drift 4.19 7.67 3.64 25.80 51.99 2.29 0.32 4.10 0.37 70.00
Fall RP-141-2 SC Plankton Net 0.00 0.00 32.50 32.50 35.00 0.00 0.00 0.00 0.10 40.00
Fall RP-141-3 MC Drift 0.00 3.36 0.95 14.36 12.77 1.00 7.41 60.14 0.23 65.35
Fall RP-141-4 US Plankton Net 0.00 0.00 2.78 36.11 2.78 0.00 27.78 30.56 0.02 84.57
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 22 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.2-7. Mean drift density and taxonomic richness values from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Whiskers Slough Focus area (FA-104) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat Type
Sampling
Device
Drift
Density
(#/ft3)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Chironomid
Taxa
Avg (Total)
Zooplankton
Taxa
Avg (Total)
Other Non-
Insect
(T)Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-104-1 TM Drift 0.040 26.5 (40) 3 (4) 13 (17) 0 7 (13) 2.77 0.85
Spr RP-104-2 SS Drift 0.058 9 (15) 2 (3) 4.5 (8) 0 0 1.38 0.64
Spr RP-104-3 MC Drift 0.101 16.5 (27) 1.5 (2) 8.5 (14) 0 2 (4) 2.49 0.90
Spr RP-104-4 US Plankton Net 1.125 3.6 (13) 0.2 (1) 0.2 (1) 1.8 (6) 1 (4) 1.38 0.90
Spr RP-104-5 SC Drift 0.129 33 (49) 3 (4) 17 (26) 0 5.5 (8) 2.73 0.78
Sum RP-104-1 TM Drift 0.054 20.5 (27) 2.5 (3) 13 (16) 0 5 (8) 2.34 0.77
Sum RP-104-2 SS Plankton Net 5.420 7.4 (15) 0.8 (2) 3.4 (7) 1.8 (3) 0.8 (2) 1.26 0.71
Sum RP-104-3 MC Drift 0.020 7 (14) 2 (4) 2.5 (5) 0 1.5 (3) 1.24 0.47
Sum RP-104-4 US Plankton Net 9.643 15.6 (31) 0.4 (1) 3.4 (8) 7.6 (13) 3.4 (6) 2.07 0.76
Sum RP-104-5 SC Drift 0.023 15.5 (24) 7 (10) 4.5 (8) 0 1.5 (2) 2.46 0.90
Post Storm RP-104-2 SS Plankton Net 0.561 3.4 (11) 0.4 (1) 0.8 (2) 1.6 (5) 0.4 (2) 1.10 0.69
Sum RP-104-1 TM Drift 0.026 18 (26) 3 (3) 9 (15) 0 4.5 (6) 2.41 0.83
Fall RP-104-2 SS Plankton Net 0.189 1.6 (7) 0.2 (1) 0.8 (3) 0.2 (1) 0.4 (2) 0.51 0.29
Fall RP-104-3 MC Drift 0.039 17.5 (26) 3.5 (5) 4 (8) 0 8 (10) 2.05 0.72
Fall RP-104-4 US Plankton Net 18.475 12.4 (26) 0 3.8 (10) 6.2 (9) 2 (5) 2.12 0.85
Fall RP-104-5 SC Plankton Net 0.035 0.4 (2) 0 0 0.2 (1) 0.2 (1) 0.64 0.92
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 23 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.2-8. Mean taxonomic composition metric values (n=5) from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Whiskers Slough Focus area (FA-104) in the Middle River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat Type
Sampling
Device
Percent
Mayflies
Percent
Stoneflies
Percent
Caddisflies
Percent Chiro-nomids
Percent Other Diptera
Percent Other insects
Percent Zoo-plankton
Percent Other
Non-insects
EPT:Chiro
Ratio
Percent Top 3 Taxa
Spr RP-104-1 TM Drift 1.09 0.68 8.06 57.37 7.24 2.94 4.08 18.53 0.14 41.00
Spr RP-104-2 SS Drift 1.64 61.20 0.00 18.28 14.78 4.10 0 0.00 0.77 82.97
Spr RP-104-3 MC Drift 5.93 0.00 0.00 52.46 28.91 8.62 1.02 3.06 0.10 47.61
Spr RP-104-4 US Plankton Net 0.00 0.00 1.72 3.33 2.52 0.00 72.78 19.65 0.20 48.25
Spr RP-104-5 SC Drift 3.46 2.20 0.00 57.41 23.35 4.17 2.50 6.92 0.09 55.11
Sum RP-104-1 TM Drift 0.30 0.00 3.99 82.96 0.00 0.00 0 12.75 0.05 56.43
Sum RP-104-2 SS Plankton Net 0.27 0.00 0.88 71.49 0.27 0.00 21.76 5.33 0.02 87.39
Sum RP-104-3 MC Drift 4.00 16.00 4.00 36.00 16.00 4.00 0 20.00 0.40 41.71
Sum RP-104-4 US Plankton Net 0.00 0.00 0.39 12.76 1.18 0.00 57.99 27.67 0.04 61.85
Sum RP-104-5 SC Drift 19.88 16.43 17.35 26.45 6.41 5.17 0 8.30 0.67 47.25
Post
Storm RP-104-2 SS Plankton Net 0.00 0.00 9.31 27.13 2.71 0.00 56.96 3.89 0.24 68.46
Sum RP-104-1 TM Drift 9.55 4.06 6.69 22.51 17.24 1.43 7.47 31.05 0.47 53.23
Fall RP-104-2 SS Plankton Net 0.00 0.00 21.30 56.80 0.00 0.00 7.10 14.79 0.06 55.00
Fall RP-104-3 MC Drift 0.00 4.42 1.47 5.88 19.50 0.89 29.03 38.81 0.50 67.98
Fall RP-104-4 US Plankton Net 0.00 0.00 0.00 21.43 0.13 0.58 42.88 34.97 0.00 58.37
Fall RP-104-5 SC Plankton Net 0.00 0.00 0.00 0.00 0.00 0.00 66.67 33.33 0.00 20.00
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 24 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.2-9. Mean drift density and taxonomic richness values from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Montana Creek area (RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study.
Event Site
Macro-
habitat Type
Sampling
Device
Drift
Density
(#/ft3)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Chironomid
Taxa
Avg (Total)
Zooplankton
Taxa
Avg (Total)
Other Non-
Insect
(T)Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-81-1 US Plankton Net 4.983 9.2 (24) 0 2.8 (8) 5 (11) 1 (3) 1.67 0.76
Spr RP-81-2 TM Drift 0.215 35 (46) 8.5 (11) 15.5 (20) 0 7 (10) 2.52 0.71
Spr RP-81-3 MC Drift 0.113 18 (30) 1.5 (2) 7 (12) 0 3.5 (5) 2.41 0.83
Spr RP-81-4 SC Drift 0.050 13.5 (20) 1.5 (2) 7.5 (10) 0 1 (2) 2.27 0.91
Spr RP-81-5 SC, Above
TM Drift 0.097 21.5 (32) 3 (4) 9.5 (15) 0 4.5 (7) 2.74 0.90
Sum RP-81-1 US Plankton Net 7.960 5.6 (22) 0.4 (2) 2 (8) 1.8 (6) 1.2 (5) 1.11 0.89
Sum RP-81-2 TM Drift - - - - - - - -
Sum RP-81-3 MC Drift 0.020 28.5 (40) 7 (9) 12.5 (18) 0 4 (5) 3.15 0.94
Sum RP-81-4 SC Drift 0.071 23 (36) 5.5 (9) 7 (10) 0 5 (8) 2.95 0.95
Sum RP-81-5 SC, Above
TM Drift 0.085 33 (51) 6.5 (8) 10.5 (18) 0 2.5 (4) 3.05 0.87
Sum RP-81-1 US Drift 0.204 20.5 (29) 1 (2) 4.5 (7) 0 9 (11) 1.36 0.45
Fall RP-81-2 TM Drift 0.074 44.5 (58) 6 (8) 19.5 (27) 0 11.5 (13) 3.14 0.83
Fall RP-81-3 MC Drift 0.034 29 (46) 5 (9) 9 (16) 0 9 (13) 2.85 0.86
Fall RP-81-4 SC Drift 0.030 22.5 (30) 8 (10) 2.5 (4) 0 5.5 (7) 1.94 0.62
Fall RP-81-5 SC, Above
TM Drift 0.252 22 (34) 5 (8) 2 (4) 0 9 (13) 2.20 0.71
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 25 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.2-10. Mean taxonomic composition metric values (n=5) from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites within the Montana Creek area (RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study.
Event Site Macro-habitat Type
Sampling Device Percent Mayflies Percent Stoneflies Percent Caddisflies
Percent Chiro-nomids
Percent Other
Diptera
Percent
Other
insects
Percent
Zoo-
plankton
Percent Other Non-insects
EPT:Chiro Ratio
Percent Top 3 Taxa
Spr RP-81-1 US Plankton Net 0.00 0.00 0.00 13.83 0.39 0.60 77.19 7.99 0.00 73.90
Spr RP-81-2 TM Drift 14.39 0.63 2.81 61.15 13.57 0.15 0.43 6.86 0.23 57.12
Spr RP-81-3 MC Drift 2.44 1.22 0.00 32.86 41.54 6.10 1.22 14.63 0.11 52.73
Spr RP-81-4 SC Drift 11.04 1.35 0.00 48.79 29.36 4.05 0 5.41 0.20 49.01
Spr RP-81-5
SC,
Above
TM
Drift 8.30 4.68 0.00 32.52 16.21 7.01 3.95 22.33 0.30 40.96
Sum RP-81-1 US Plankton Net 0.00 0.00 0.83 18.95 0.83 0.00 11.85 67.54 0.01 73.77
Sum RP-81-2 TM Drift - - 27.48
Sum RP-81-3 MC Drift 4.96 12.40 4.96 53.23 3.31 7.28 0 13.85 0.29 29.70
Sum RP-81-4 SC Drift 7.72 9.45 5.72 35.26 14.33 11.17 0 16.34 0.38 37.62
Sum RP-81-5
SC,
Above
TM
Drift 19.55 9.41 12.22 31.98 6.13 13.88 0 6.83 0.56 88.29
Sum RP-81-1 US Drift 0.00 0.19 0.15 3.25 1.90 1.80 24.5 68.22 0.11 38.13
Fall RP-81-2 TM Drift 2.33 4.91 3.62 28.65 4.98 3.82 16.87 34.81 0.27 42.58
Fall RP-81-3 MC Drift 1.59 3.93 1.59 19.17 5.04 8.60 24.65 35.44 0.32 70.90
Fall RP-81-4 SC Drift 1.59 22.71 50.02 3.43 3.61 8.57 0.88 9.19 0.96 61.91
Fall RP-81-5
SC,
Above
TM
Drift 1.28 3.86 16.72 4.51 3.03 4.10 47.33 19.16 0.85 73.90
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.3-1. Mean density and taxonomic richness values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites on the Talkeetna River (RP-TKA) for the River Productivity Study.
Event Site
Macro-
habitat
Type
Sampling
Device
Density
(sq m)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Mayfly (E)
Taxa
Avg (Total)
Stonefly
(P) Taxa
Avg (Total)
Caddisfly
(T)Taxa
Avg (Total)
Chironomid
Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-TKA-1 SC Hess 548.8 12 (23) 5 (9) 3.4 (6) 1.4 (2) 0.2 (1) 5.4 (11) 1.90 0.77
Spr RP-TKA-2 US Petite
Ponar 6699.5 13.2 (28) 0.2 (1) 0 (0) 0 (0) 0.2 (1) 9 (19) 1.44 0.59
Spr RP-TKA-3 SS Hess 13040.1 28.4 (51) 10 (16) 6 (8) 3.2 (5) 0.8 (3) 14.4 (23) 2.19 0.65
Sum RP-TKA-1 SC Hess 820.9 12.6 (27) 5.2 (10) 1.8 (5) 3 (4) 0.4 (1) 5.8 (12) 1.73 0.69
Sum RP-TKA-2 US Petite
Ponar 1145.3 8.6 (29) 0 (0) 0 (0) 0 (0) 0 (0) 6.8 (24) 1.49 0.84
Sum RP-TKA-3 SS Hess 5311.0 20.4 (39) 7.2 (12) 3.2 (4) 3.2 (6) 0.8 (2) 9.2 (16) 1.93 0.64
Fall RP-TKA-1 SC Hess 541.9 11 (23) 5.4 (9) 1.4 (3) 3.8 (5) 0.2 (1) 3.2 (8) 2.05 0.86
Fall RP-TKA-2 US Petite
Ponar 5984.7 17.4 (38) 0 (0) 0 (0) 0 (0) 0 (0) 13 (29) 1.89 0.67
Fall RP-TKA-3 SS Hess 4719.0 27.6 (49) 11.2 (17) 4.4 (6) 4.6 (6) 2.2 (5) 10.8 (22) 2.67 0.80
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.3-2. Mean taxonomic composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites on the Talkeetna River (RP-TKA) for the River Productivity Study.
Event Site Macro-habitat
Type
Sampling Device Percent Mayflies Percent Stoneflies Percent Caddisflies
Percent Chiro-
nomids
Percent Other
Diptera
Percent Other
insects
Percent Non-
insect
EPT:Chiro Ratio Percent Top Taxa
Percent Top 3
Taxa
Spr RP-TKA-1 SC Hess 16.90 19.65 0.42 56.65 4.15 0.00 2.24 0.40 39.38 68.28
Spr RP-TKA-2 US Petite
Ponar 0.00 0.00 0.13 43.96 1.46 0.00 54.45 0.01 54.19 79.53
Spr RP-TKA-3 SS Hess 8.36 8.82 0.23 77.35 0.80 0.00 4.45 0.18 36.10 66.35
Sum RP-TKA-1 SC Hess 5.02 19.32 0.50 70.52 1.11 0.00 3.53 0.26 47.24 73.37
Sum RP-TKA-2 US Petite
Ponar 0.00 0.00 0.00 69.30 0.00 0.00 30.70 0.00 45.08 79.78
Sum RP-TKA-3 SS Hess 4.34 20.28 0.43 61.56 1.49 0.00 11.90 0.29 33.48 71.27
Fall RP-TKA-1 SC Hess 8.41 36.14 0.59 41.26 12.79 0.00 0.81 0.53 27.65 60.12
Fall RP-TKA-2 US Petite
Ponar 0.00 0.00 0.00 65.02 5.12 0.00 29.86 0.00 40.82 71.77
Fall RP-TKA-3 SS Hess 12.28 43.92 5.26 28.72 2.79 0.00 7.02 0.68 21.55 44.71
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.3-3. Mean functional feeding group composition metric values (n=5) from Hess and petite Ponar grab samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites on the Talkeetna River (RP-TKA) for the River Productivity Study.
Event Site Macro-habitat Type
Sampling Device
Percent Collector Gatherers
Percent Collector Filterers
Percent Scrapers Percent Shredders Percent Predators Percent Parasites
Percent Other FFGs
Spr RP-TKA-1 SC Hess 64.43 3.65 9.22 1.92 20.78 0.00 0.00
Spr RP-TKA-2 US Petite
Ponar 82.83 5.64 0.00 2.86 2.07 5.13 1.47
Spr RP-TKA-3 SS Hess 83.93 0.69 3.90 2.02 9.19 0.22 0.05
Sum RP-TKA-1 SC Hess 74.46 0.44 4.17 16.59 4.34 0.00 0.00
Sum RP-TKA-2 US Petite
Ponar 80.75 8.21 0.00 8.33 2.38 0.33 0.00
Sum RP-TKA-3 SS Hess 74.80 0.05 2.82 16.72 5.61 0.00 0.00
Fall RP-TKA-1 SC Hess 43.85 10.41 5.00 21.25 19.48 0.00 0.00
Fall RP-TKA-2 US Petite
Ponar 72.68 18.21 0.08 1.08 6.96 0.57 0.41
Fall RP-TKA-3 SS Hess 40.06 0.78 4.98 35.82 18.36 0.00 0.00
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.3-4. Mean drift density and taxonomic richness values from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites on the Talkeetna River (RP-TKA) for the River Productivity Study.
Event Site
Macro-
habitat Type
Sampling
Device
Drift
Density
(#/ft3)
Taxa
Richness
Avg (Total)
EPT
Richness
Avg (Total)
Chironomid
Taxa
Avg (Total)
Zooplankton
Taxa
Avg (Total)
Other Non-
Insect
(T)Taxa
Avg (Total)
Diversity
(H')
Evenness
(J')
Spr RP-TKA-1 SC Drift 0.121 21 (27) 5 (5) 8.5 (11) 0 2 (3) 2.70 0.89
Spr RP-TKA-2 US Plankton Net 0.960 5.4 (16) 0.2 (1) 3 (10) 1.2 (2) 1 (3) 1.35 0.74
Spr RP-TKA-3 SS Drift 0.130 31 (43) 6.5 (9) 15.5 (20) 0 4.5 (7) 2.43 0.71
Sum RP-TKA-1 SC Drift 0.072 22.5 (34) 5 (7) 12 (18) 0 2.5 (3) 2.55 0.82
Sum RP-TKA-2 US Plankton Net 1.499 4.2 (16) 0.6 (2) 2 (7) 1.2 (4) 0.4 (2) 1.30 0.85
Sum RP-TKA-3 SS Drift 0.071 40.5 (56) 8.5 (11) 17.5 (26) 0 7 (10) 2.87 0.78
Fall RP-TKA-1 SC Drift 0.114 27 (38) 6.5 (8) 6.5 (10) 0 5 (7) 2.52 0.77
Fall RP-TKA-2 US Plankton Net 1.870 5.4 (14) 0.4 (1) 1.8 (5) 1.6 (3) 1.4 (4) 1.51 0.92
Fall RP-TKA-3 SS Drift 0.041 18.5 (28) 7 (9) 4 (6) 0 4 (7) 2.27 0.78
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Table A3.3-5. Mean taxonomic composition metric values (n=5) from drift net and plankton tow samples collected in 2013 during three index events (Spr= Spring, Sum=Summer, Fall) for sites on the Talkeetna River (RP-TKA) for the River Productivity Study
Event Site
Macro-
habitat Type
Sampling
Device
Percent
Mayflies
Percent
Stoneflies
Percent
Caddisflies
Percent Chiro-nomids
Percent Other Diptera
Percent Other insects
Percent Zoo-plankton
Percent Other
Non-insects
EPT:Chiro
Ratio
Percent Top 3 Taxa
Spr RP-TKA-1 SC Drift 6.96 12.03 0.00 49.16 19.19 5.06 7.59 0.28 38.92
Spr RP-TKA-2 US Plankton
Net 1.49 0.00 0.00 42.44 0.00 0.00 29.10 26.96 0.05 75.40
Spr RP-TKA-3 SS Drift 12.67 7.29 0.00 68.74 5.79 1.16 4.34 0.23 58.45
Sum RP-TKA-1 SC Drift 4.14 5.95 12.01 59.07 2.00 3.05 13.78 0.27 53.10
Sum RP-TKA-2 US Plankton
Net 0.00 1.66 3.99 67.11 0.00 0.00 22.96 4.27 0.04 69.06
Sum RP-TKA-3 SS Drift 2.77 10.01 12.69 53.03 3.92 3.83 13.75 0.33 44.38
Fall RP-TKA-1 SC Drift 1.67 8.08 20.35 34.56 18.64 6.82 9.87 0.47 58.85
Fall RP-TKA-2 US Plankton
Net 0.00 0.00 4.67 45.39 1.17 0.00 35.38 13.40 0.20 73.36
Fall RP-TKA-3 SS Drift 6.75 18.06 29.22 27.59 8.61 1.89 7.87 0.68 59.58
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Table A3.4-1. Mean δ13C and δ15N ± SD for all sample types collected at FA 81 during spring sampling.
Spring Focus Area 81 Upland Slough (RP-81-1) Tributary Mouth (RP-81-2) Main Channel (RP-81-3) Side Channel (RP-81-4)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae -32.7 ± 0.7 -1.5 ± 1.4 3 -29.4 ± 1.8 1.6 ± 1.5 3 - - - -24.9 ± 1.4 6.3 ± 4.6 2
Organic matter - drift -28.1 ± 0.8 1.3 ± 4.0 2 -27.8 ± 1.1 -1.8 ± 0.2 2 - - - -27.3 ± 0.2 -2.4 ± 0.9 2
Organic matter - benthic -30.7 ± 0.0 -0.8 ± 1.5 2 -28.8 ± 0.0 -2.1 ± 0.4 3 - - - -28.3 ± 0.5 -2.8 ± 0.5 3
Salmon carcass - - - - - - - - - - - -
Salmon eggs - - - - - - - - - - - -
Invertebrates
Aquatic Invertebrates -32.1 ± 3.4 4.8 ± 1.6 8 -31.6 ± 4.3 3.6 ± 1.1 9 - - - -29.7 ± 3.7 1.7 ± 0.5 4
Benthic - collectors -33.3 ± 0.4 4.7 ± 1.6 3 -29.6 ± 0.5 2.9 ± 0.8 3 - - - - - -
Benthic - grazers -29.354 2.669 1 -30.2 ± 2.2 4.7 ± 0.3 3 - - - -28.077 1.262 1
Benthic - predators -32.0 ± 5.9 5.8 ± 1.6 3 - - - - - - -30.3 ± 4.3 1.9 ± 0.5 3
Benthic - shredders -31.966 4.06 1 -34.9 ± 6.8 3.1 ± 1.2 3 - - - - - -
Emergents -31.0 ± 0.5 5.2 ± 0.1 3 - - - -26.2 ± 0.1 2.2 ± 1.9 3 -25.5 ± 0.4 1.7 ± 0.2 2
Terrestrial -29.9 ± 1.1 5.0 ± 0.3 2 - - - - - - - - -
Fish
Rainbow trout - juveniles -26.1 ± 0.0 8.0 ± 0.3 2 -25.5 ± 3.1 7.7 ± 0.3 5 - - - - - -
Rainbow trout - adults - - - - - - - - - - - -
Chinook salmon - juveniles -26.8 ± 2.4 6.8 ± 0.7 6 -25.9 ± 0.6 8.0 ± 1.3 8 - - - - - -
Coho salmon - juveniles -28.4 ± 2.4 7.8 ± 0.3 8 -27.4 ± 2.3 8.9 ± 1.7 8 - - - - - -
Totals 44 44 3 17
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Table A3.4-2. Mean δ13C and δ15N ± SD for all sample types collected at FA 81 during summer sampling.
Summer Focus Area 81 Upland Slough (RP-81-1) Tributary Mouth (RP-81-2) Main Channel (RP-81-3) Side Channel (RP-81-4)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae -31.0 ± 0.7 -3.3 ± 4.5 3 -29.7 ± 1.7 6.5 ± 2.9 3 -23.0 ± 0.8 3.3 ± 4.5 3 -25.4 ± 0.4 4.0 ± 1.0 3
Organic matter - drift -30.4 ± 0.1 0.5 ± 0.3 2 -28.8 ± 0.4 0.7 ± 1.7 2 -27.7 ± 0.4 -4.3 ± 0.2 2 -28.0 ± 0.6 -3.4 ± 1.4 2
Organic matter - benthic -28.5 ± 1.2 -3.3 ± 1.0 3 -28.9 ± 0.1 -1.6 ± 1.2 3 -20.5 ± 17. -4.1 ± 5.6 3 -27.7 ± 0.3 -4.6 ± 0.3 3
Salmon carcass -20.481 10.446 1 -19.9 ± 0.3 10.0 ± 0.6 4 - - - - - -
Salmon eggs - - - - - - - - - - - -
Invertebrates
Aquatic Invertebrates -33.2 ± 2.0 4.1 ± 1.2 9 -30.6 ± 1.8 4.9 ± 1.4 9 -26.0 ± 1.0 1.7 ± 3.1 8 -25.7 ± 0.4 1.0 ± 2.8 7
Benthic - collectors -34.9 ± 2.3 4.8 ± 0.7 3 -30.8 ± 3.0 4.2 ± 2.2 3 -26.9 ± 1.7 1.7 ± 0.2 2 -25.778 2.365 1
Benthic - grazers - - - -30.6 ± 1.5 5.0 ± 1.3 2 -26.4 ± 0.5 -2. ± 2.6 2 -25.7 ± 0.5 -1.7 ± 1.8 3
Benthic - predators -32.3 ± 2.1 3.7 ± 0.3 3 -30.1 ± 1.4 5.8 ± 0.6 3 -25.5 ± 0.4 4.5 ± 1.0 3 -25.8 ± 0.4 3.3 ± 0.5 3
Benthic - shredders -32.4 ± 0.7 3.7 ± 2.1 3 -31.644 4.31 1 -25.013 1.608 1 - - -
Emergents -32.6 ± 1.1 5.2 ± 0.5 6 -29.0 ± 1.1 3.6 ± 1.1 3 -24.5 ± 0.2 2.6 ± 0.4 3 -25.5 ± 0.3 1.7 ± 0.7 4
Terrestrial -24.9 ± 0.5 3.2 ± 0.7 2 -25.5 ± 1.9 4.5 ± 1.7 3 -25.9 ± 2.8 0.9 ± 0.2 2 -26.1 ± 0.4 1.1 ± 1.0 2
Fish
Rainbow trout - juveniles - - - - - - - - - - - -
Rainbow trout - adults - - - - - - - - - - - -
Chinook salmon - juveniles - - - -24.089 8.214 1 - - - - - -
Coho salmon - juveniles - - - -27.8 ± 2.6 9.1 ± 1.3 4 - - - - - -
Totals 35 41 26 28
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Table A3.4-3. Mean δ13C and δ15N ± SD for all sample types collected at FA 81 during fall sampling.
Fall Focus Area 81 Upland Slough (RP-81-1) Tributary Mouth (RP-81-2) Main Channel (RP-81-3) Side Channel (RP-81-4)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae -30.6 ± 0.9 1.3 ± 1.2 3 -31.0 ± 1.9 3.7 ± 0.3 3 -25.3 ± 0.1 7.0 ± 1.1 3 -26.5 ± 0.7 4.2 ± 3.1 3
Organic matter - drift -28.9 ± 0.0 -4. ± 2.4 2 -28.5 ± 0.6 -4. ± 3.2 2 -27.9 ± 0.2 -3. ± 0.5 2 -28.8 ± 0.2 -3. ± 0.3 2
Organic matter - benthic -30.0 ± 0.2 -6. ± 2.5 3 -28.6 ± 1.4 -1. ± 0.6 3 -28.1 ± 0.7 -4. ± 0.9 3 -27.1 ± 1.0 -3. ± 1.6 3
Salmon carcass - - - - - - - - - - - -
Salmon eggs - - - - - - - - - - - -
Invertebrates
Aquatic Invertebrates -30.8 ± 6.2 2.9 ± 2.9 8 -28.3 ± 1.6 4.6 ± 1.4
1
1 -27.7 ± 1.5 0.3 ± 2.1 8 -27.1 ± 0.9 0.8 ± 2.4
1
2
Benthic - collectors -30.8 ± 8.1 1.7 ± 3.6 4 -28.6 ± 0.6 4.9 ± 0.5 3 -29.1 ± 1.0 0.0 ± 1.3 3 -27.0 ± 0.3 0.9 ± 2.0 3
Benthic - grazers -32.7 ± 7.4 4.7 ± 2.2 2 -27.1 ± 1.8 5.0 ± 2.1 3 -26.7 2.3 1 -26.3 ± 0.3 -1. ± 2.9 3
Benthic - predators -29.8 4.5 1 -30.3 ± 2.6 4.0 ± 0.0 2 -26.7 ± 2.2 0.8 ± 4.3 2 -27.3 ± 0.7 2.4 ± 1.2 3
Benthic - shredders -28.5 3.1 1 -27.8 ± 0.4 4.4 ± 2.1 3 -27.2 ± 0.5 -0. ± 1.3 2 -27.5 ± 1.7 1.9 ± 1.5 3
Emergents - - - - - - - - - - - -
Terrestrial -31.7 ± 6.0 1.2 ± 2.9 4 - - - -25.5 ± 0.9 1.7 ± 1.1 3 -26.2 ± 0.9 -1.0 ± 1.4 2
Fish
Rainbow trout - juveniles - - - - - - - - - - - -
Rainbow trout - adults - - - - - - - - - - - -
Chinook salmon - juveniles -26.1 8.4 1 - - - - - - - - -
Coho salmon - juveniles -26.1 ± 1.6 8.4 ± 1.8 4 -26.7 ± 1.9 9.0 ± 0.3 2 - - - - - -
Totals
3
3
3
2
2
7
3
4
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Table A3.4-4. Mean δ13C and δ15N ± SD for all sample types collected at FA 104 during spring sampling.
Spring Focus Area 104 Tributary Mouth (RP-104-1) Side Slough (RP-104-2) Main Channel (RP-104-3) Upland Slough (RP-104-4) Side Channel (RP-104-5)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae -33.0 ± 0.5 2.9 ± 0.2 3 -28.8 ± 2.5 2.2 ± 0.4 3 -24.8 ± 0.9 4.1 ± 1.2 3 -28.3 ± 0.6 2.1 ± 0.8 3 -23.9 ± 0.2 3.2 ± 0.1 3
Organic matter - drift -27.3 ± 0.8 -0.1 ± 0.3 2 -27.6 ± 0.3 -0.2 ± 0.4 2 -27.2 ± 0.1 -1.2 ± 0.1 2 -28.8 ± 2.2 0.3 ± 0.7 2 -27.0 ± 0.1 -0.3 ± 0.4 2
Organic matter - benthic -27.8 ± 0.5 0.6 ± 1.2 3 -29.6 ± 2.6 0.4 ± 1.3 3 -27.7 ± 0.5 -1.1 ± 0.5 3 -28.5 ± 0.4 -1.0 ± 1.1 3 -28.0 ± 0.2 -0.7 ± 0.3 3
Salmon carcass - - - - - - - - - - - - - - -
Salmon eggs - - - - - - - - - - - - - - -
Invertebrates
Aquatic Invertebrates -32.7 ± 2.4 5.0 ± 1.2 12 -32.8 ± 2.1 5.2 ± 1.8 9 -30.0 2.6 1 -35.6 ± 3.2 3.9 ± 1.1 5 -31.0 ± 1.7 4.1 ± 1.6 5
Benthic - collectors -31.9 ± 2.6 4.5 ± 0.4 3 -33.6 ± 1.1 3.9 ± 0.5 3 -30.0 2.6 1 -37.7 ± 1.7 3.3 ± 1.0 3 -29.7 3.1 1
Benthic - grazers -31.5 ± 0.1 4.5 ± 0.2 3 -31.3 ± 1.6 4.5 ± 0.6 2 - - - - - - - - -
Benthic - predators -32.3 ± 1.6 6.3 ± 0.1 3 -34.4 ± 0.6 5.6 ± 0.9 3 - - - -32.3 ± 0.4 4.7 ± 1.1 2 -31.9 ± 1.6 5.2 ± 1.1 3
Benthic - shredders -35.0 ± 3.4 5.0 ± 2.1 3 -28.6 9.6 1 - - - - - - -29.6 2.2 1
Emergents -31.8 ± 1.4 3.5 ± 0.4 3 -31.9 ± 1.6 2.0 ± 0.3 3 - - - -34.3 ± 1.1 2.9 ± 1.0 3 - - -
Terrestrial -27.6 3.9 1 -30.0 ± 4.9 4.5 ± 1.2 2 - - - -27.6 ± 1.7 4.5 ± 3.3 3 -28.3 ± 2.6 3.0 ± 2.4 3
Fish
Rainbow trout - juveniles - - - - - - - - - - - - - - -
Rainbow trout - adults -24.0 12.0 1 - - - - - - - - - - - -
Chinook salmon - juveniles -27.4 ± 1.2 8.3 ± 0.3 8 - - - - - - - - - - - -
Coho salmon - juveniles - - - - - - - - - - - - - - -
Totals 45 31 10 24 21
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Table A3.4-5. Mean δ13C and δ15N ± SD for all sample types collected at FA 104 during summer sampling.
Summer Focus Area 104 Tributary Mouth (RP-104-1) Side Slough (RP-104-2) Main Channel (RP-104-3) Upland Slough (RP-104-4) Side Channel (RP-104-5)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae -30.9 ± 0.0 1.8 ± 0.1 3 -38.0 ± 2.7 0.6 ± 0.9 3 -22.4 ± 1.1 2.6 ± 2.8 3 -24.6 ± 6.1 -2.6 ± 2.0 3 -23.5 ± 3.6 1.4 ± 1.7 3
Organic matter - drift -27.8 ± 0.4 -0.5 ± 0.0 2 -29.5 ± 0.4 -0.6 ± 0.6 2 -27.4 ± 0.1 -2.6 ± 0.1 2 -28.7 ± 0.3 -0.2 ± 0.8 2 -27.1 ± 0.0 -4.0 ± 0.1 2
Organic matter - benthic -28.0 ± 0.3 -1.6 ± 0.8 3 -33.2 ± 4.6 -2.6 ± 0.8 3 -26.5 ± 0.5 -4.0 ± 0.2 3 -25.3 ± 3.8 -2.9 ± 1.4 3 -26.2 ± 0.9 -4.4 ± 0.7 3
Salmon carcass - - - - - - - - - - - - - - -
Salmon eggs - - - - - - - - - - - - - - -
Invertebrates
Aquatic Invertebrates -33.0 ± 1.1 4.6 ± 1.1 6 -38.9 ± 1.7 1.9 ± 2.1 9 -27.7 ± 1.8 3.1 ± 1.5 7 -34.0 ± 1.8 2.7 ± 1.2 10 -26.2 ± 0.7 3.5 ± 0.9 9
Benthic - collectors -32.9 ± 1.5 4.3 ± 0.5 3 -38.5 ± 2.6 0.9 ± 1.7 3 -26.5 ± 1.2 2.1 ± 1.2 3 -34.0 ± 1.5 2.8 ± 0.2 3 -25.9 ± 1.1 3.4 ± 1.3 3
Benthic - grazers - - - -38.7 ± 2.1 1.2 ± 0.3 2 -27.5 5.0 1 - - - -26.3 ± 0.3 3.8 ± 1.1 3
Benthic - predators -33.4 ± 1.1 5.8 ± 0.3 2 -39.5 ± 1.5 3.8 ± 2.5 3 -29.0 ± 1.9 3.6 ± 1.2 3 -34.4 ± 2.9 3.1 ± 1.8 4 -26.4 ± 0.7 3.4 ± 0.6 3
Benthic - shredders -32.9 3.0 1 -38.6 0.4 1 - - - -33.4 ± 0.4 2.1 ± 0.8 3 - - -
Emergents -33.1 ± 1.1 4.8 ± 0.7 2 -31.0 ± 2.3 5.4 ± 1.4 3 -26.0 ± 0.6 3.4 ± 0.9 3 -35.1 ± 0.5 2.6 ± 0.4 3 - - -
Terrestrial - - 1 -27.0 ± 1.3 2.5 ± 1.2 3 -26.0 ± 0.7 1.3 ± 2.8 3 -27.8 ± 2.8 2.8 ± 1.9 3 -25.4 ± 1.0 3.3 ± 1.9 2
Fish
Rainbow trout - juveniles - - - - - - - - - - - - - - -
Rainbow trout - adults - - - -22.9 ± 2.2 11.2 ± 0.6 9 - - - - - - - - -
Chinook salmon - juveniles -27.1 ± 0.9 9.2 ± 0.5 7 -27.4 ± 3.8 8.8 ± 0.7 8 - - - -28.7 ± 2.0 7.3 ± 1.3 8 -26.6 ± 3.4 9.0 ± 1.0 8
Coho salmon - juveniles -27.1 ± 1.5 8.6 ± 1.0 8 -27.7 ± 1.3 8.8 ± 0.5 8 - - - -28.2 ± 2.2 7.4 ± 1.0 7 -25.9 ± 2.0 8.1 ± 0.9 7
Totals 38 57 28 49 43
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Table A3.4-6. Mean δ13C and δ15N ± SD for all sample types collected at FA 104 during fall sampling.
Fall Focus Area 104 Tributary Mouth (RP-104-1) Side Slough (RP-104-2) Main Channel (RP-104-3) Upland Slough (RP-104-4) Side Channel (RP-104-5)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae -31.1 ± 1.2 6.4 ± 3.0 3 -31.9 ± 0.6 3.4 ± 3.8 3 -30.6 ± 1.0 3.8 ± 0.2 3 -29.7 ± 1.5 -0. ± 0.4 3 -27.5 ± 4.1 0.1 ± 2.0 3
Organic matter - drift -27.5 ± 0.3 0.2 ± 0.6 2 -26.1 ± 0.8 -0. ± 1.6 2 -26.9 ± 0.4 -1. ± 0.9 2 -27.4 ± 0.2 -0. ± 1.6 2 -28.6 ± 1.7 -0.4 ± 0.6 2
Organic matter - benthic -28.5 ± 1.1 -1. ± 0.7 3 -30.7 ± 4.4 -0. ± 0.8 3 -27.3 ± 0.9 -1. ± 0.9 3 -26.4 ± 0.5 -2. ± 0.2 3 -29.9 ± 0.8 -1.2 ± 0.8 3
Salmon carcass -19.2 11.9 1 - - - - - - - - - - - -
Salmon eggs - - - - - - - - - - - - - - -
Invertebrates
Aquatic Invertebrates -32.0 ± 2.3 4.8 ± 1.1 11 -35.2 ± 3.2 2.8 ± 0.9 10 -27.3 ± 1.3 1.6 ± 1.6 8 -31.8 ± 4.8 1.4 ± 2.1 8 -26.0 ± 2.8 1.2 ± 3.3 11
Benthic - collectors -31.8 ± 2.0 4.8 ± 0.9 3 -36.7 ± 2.3 2.8 ± 1.3 3 -27.9 ± 0.3 1.9 ± 0.4 2 -35.0 ± 3.5 2.9 ± 1.0 3 -26.2 ± 2.6 3.6 ± 4.5 3
Benthic - grazers -34.2 ± 3.1 5.1 ± 0.6 2 -38.2 3.4 1 -27.9 ± 1.6 2.9 ± 0.7 2 - - - -27.3 ± 0.1 3.4 ± 0.2 2
Benthic - predators -32.1 ± 0.9 6.0 ± 0.1 3 -34.2 ± 2.0 3.2 ± 0.8 3 -27.1 ± 1.8 1.0 ± 2.2 3 -28.1 ± 5.8 0.3 ± 3.2 3 -24.4 ± 5.1 -1.6 ± 2.9 3
Benthic - shredders -30.6 ± 3.2 3.4 ± 0.9 3 -33.6 ± 4.8 2.3 ± 1.0 3 -25.9 0 1 -32.6 ± 0.3 1.0 ± 0.2 2 -26.5 ± 0.9 0.3 ± 0.7 3
Emergents -31.3 3.4 1 -30.3 3.7 1 -30.1 1.5 1 -34.8 ± 4.5 3.3 ± 0.6 3 - - -
Terrestrial -26.2 2.3 1 -32.6 ± 4.3 2.4 ± 1.3 2 -28.1 ± 2.6 3.0 ± 0.8 2 -28.6 7.7 1 -25.2 ± 1.1 1.5 ± 2.8 3
Fish
Rainbow trout - juveniles - - - - - - - - - - - - - - -
Rainbow trout - adults -22.0 ± 4.0 11.5 ± 1.4 7 - - - - - - - - - - - -
Chinook salmon - juveniles -25.3 ± 2.1 10. ± 1.3 7 -22.3 10.0 1 - - - -24.3 9.8 1 -27.1 ± 4.7 8.8 ± 1.8 3
Coho salmon - juveniles -24.9 ± 2.6 8.9 ± 1.8 7 -26.4 ± 2.8 9.6 ± 1.2 8 - - - -28.7 ± 1.9 7.9 ± 0.6 5 -23.4 ± 2.0 9.9 ± 2.0 9
Totals 54 40 27 34 45
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Table A3.4-7. Mean δ13C and δ15N ± SD for all sample types collected at FA 141 during spring sampling.
Spring Focus Area 141 Tributary Mouth (RP-141-1) Side Channel (RP-141-2) Main Channel (RP-141-3) Upland Slough (RP-141-4)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae -26.6 ± 2.9 4.5 ± 1.0 3 -27.2 ± 0.2 1.1 ± 1.7 3 -30.3 2.9 3 -36.8 ± 1.0 -0.7 ± 0.7 3
Organic matter - drift -27.3 ± 0.4 -0.3 ± 0.2 2 -26.9 0.5 2 -27.0 ± 0.0 -0.7 ± 1.6 2 -28.0 ± 0.0 -0.7 ± 0.0 2
Organic matter - benthic -27.3 ± 1.1 -1.0 ± 0.4 3 -27.4 ± 0.2 -1.0 ± 0.4 3 -27.2 ± 0.1 -0.1 ± 0.2 3 -29.5 ± 2.3 -0.3 ± 0.5 3
Salmon carcass - - - - - - - - - - - -
Salmon eggs - - - - - - - - - - - -
Invertebrates
Aquatic Invertebrates -29.3 ± 2.8 2.9 ± 1.8 12 -29.7 ± 3.2 2.9 ± 2.0 11 -32.2 ± 4.0 2.7 ± 1.9 9 -29.6 ± 3.1 2.9 ± 2.4 10
Benthic - collectors -31.6 ± 0.8 2.5 ± 0.5 3 -31.5 ± 3.6 3.1 ± 1.4 3 -32.5 ± 5.6 0.9 ± 2.1 3 -29.5 ± 3.7 3.7 ± 0.9 3
Benthic - grazers -30.0 ± 2.7 3.0 ± 0.1 3 -30.9 ± 4.6 3.6 ± 1.7 2 -31.4 ± 1.9 3.1 ± 1.3 3 -28.3 0.9 1
Benthic - predators -26.7 ± 0.2 4.5 ± 2.7 3 -30.5 ± 1.8 4.7 ± 0.8 3 -29.7 ± 0.3 4.3 ± 0.4 2 -32.5 ± 2.3 5.6 ± 1.1 3
Benthic - shredders -28.9 ± 3.9 1.8 ± 2.3 3 -26.5 ± 0.9 0.4 ± 1.5 3 -39.0 3.7 1 -27.3 ± 1.6 0.3 ± 1.0 3
Emergents -26.9 ± 1.1 3.8 ± 2.0 3 -24.5 ± 1.0 2.8 ± 0.5 3 - - - -27.1 ± 0.0 5.0 ± 0.3 3
Terrestrial -26.1 ± 1.8 1.9 ± 1.8 2 -25.1 4.0 1 -25.4 3.6 1 -26.1 ± 1.3 2.2 ± 1.8 2
Fish
Rainbow trout - juveniles -24.3 8.7 1 - - - - - - - - -
Rainbow trout - adults - - - - - - - - - - - -
Chinook salmon - juveniles -25.3 ± 0.9 9.4 ± 0.6 8 - - - - - - - - -
Coho salmon - juveniles -27.2 ± 1.8 7.8 ± 0.9 8 - - - - - - - - -
Totals 54 34 27 33
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Table A3.4-8. Mean δ13C and δ15N ± SD for all sample types collected at FA 141 during summer sampling.
Summer Focus Area 141 Tributary Mouth (RP-141-1) Side Channel (RP-141-2) Main Channel (RP-141-3) Upland Slough (RP-141-4)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae -27.6 ± 1.0 4.7 ± 0.0 2 -25.6 -0.8 3 - - - -34.7 ± 1.0 0.2 ± 0.4 3
Organic matter - drift -29.1 ± 0.0 0.8 ± 0.6 2 -26.8 ± 0.1 -0.6 ± 0.3 2 -27.0 ± 0.0 -2.0 ± 0.1 2 -28.4 ± 0.3 1.4 ± 0.2 2
Organic matter - benthic -27.8 ± 0.5 -0.0 ± 0.5 3 -26.9 ± 0.1 -0.6 ± 1.2 3 -26.7 ± 0.4 0.9 ± 6.3 3 -29.0 ± 0.1 -1.1 ± 0.7 3
Salmon carcass -19.5 ± 0.5 10. ± 0.6 7 - - - - - - - - -
Salmon eggs -23.4 ± 0.8 11.3 ± 0.0 2 - - - - - - - - -
Invertebrates
Aquatic Invertebrates -28.0 ± 1.5 4.3 ± 1.1 12 -27.2 ± 1.2 3.2 ± 0.5 7 -26.6 ± 0.9 1.9 ± 1.0 5 -31.9 ± 4.4 2.9 ± 1.7 7
Benthic - collectors -26.7 ± 1.7 4.6 ± 0.9 3 -27.6 ± 2.0 3.0 ± 0.8 3 -26.8 ± 0.8 1.4 ± 1.1 3 -35.1 ± 3.4 2.6 ± 1.3 3
Benthic - grazers -29.4 ± 1.0 5.0 ± 0.3 3 -26.9 ± 0.5 3.3 ± 0.1 3 -26.4 ± 1.3 2.6 ± 0.5 2 - - -
Benthic - predators -28.2 ± 0.4 4.7 ± 0.8 3 -27.1 3.4 1 - - - -26.2 ± 0.0 4.8 ± 1.7 2
Benthic - shredders -27.6 ± 1.9 2.8 ± 0.8 3 - - - - - - -32.9 ± 0.1 1.5 ± 0.7 2
Emergents - - - -24.0 ± 0.1 2.3 ± 0.4 3 - - - - - -
Terrestrial -28.0 5.2 1 -25.6 ± 1.2 2.6 ± 0.9 2 -28.0 3.3 1 -26.2 7.8 1
Fish
Rainbow trout - juveniles -20.1 ± 1.0 10.8 ± 0.8 8 - - - - - - - - -
Rainbow trout - adults - - - - - - - - - - - -
Chinook salmon - juveniles -23.4 ± 1.1 9.0 ± 1.3 6 - - - - - - - - -
Coho salmon - juveniles -22.7 ± 1.8 9.3 ± 1.8 7 - - - - - - - - -
Totals 62 27 16 23
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Table A3.4-9. Mean δ13C and δ15N ± SD for all sample types collected at FA 141 during fall sampling.
Fall Focus Area 141 Tributary Mouth (RP-141-1) Side Channel (RP-141-2) Main Channel (RP-141-3) Upland Slough (RP-141-4)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae -30.5 ± 1.0 1.5 ± 1.9 3 -24.1 ± 2.5 -0.7 ± 0.8 3 -25.8 ± 0.8 3.1 ± 5.9 3 -27.1 ± 4.5 0.7 ± 1.1 3
Organic matter - drift -28.2 ± 0.4 0.6 ± 0.1 2 -27.9 ± 0.1 -1.0 ± 0.3 2 -27.0 ± 0.0 0.4 ± 1.0 2 -27.1 ± 0.4 0.6 ± 1.0 2
Organic matter - benthic -27.8 ± 0.3 2.6 ± 0.6 3 -27.1 ± 0.4 0.8 ± 0.7 3 -27.5 ± 1.0 -1.0 ± 0.6 3 -29.1 ± 1.3 -0.3 ± 0.5 3
Salmon carcass -19.4 ± 0.0 11.2 ± 0.5 3 - - - - - - -19.5 ± 1.4 11.6 ± 0.6 5
Salmon eggs - - - - - - - - - - - -
Invertebrates
Aquatic Invertebrates -27.3 ± 1.3 4.1 ± 1.1 12 -28.4 ± 2.0 2.6 ± 1.3 11 -25.7 ± 3.3 1.4 ± 1.5 5 -29.8 ± 2.7 3.1 ± 1.9 6
Benthic - collectors -27.2 ± 0.7 3.4 ± 0.9 3 -29.6 ± 3.6 2.4 ± 0.5 3 -23.8 ± 5.4 1.4 ± 1.3 2 -30.0 ± 3.9 4.7 ± 1.2 3
Benthic - grazers -28.6 ± 2.0 4.5 ± 0.7 3 -27.5 ± 0.8 1.8 ± 1.0 2 -26.4 ± 0.5 1.2 ± 2.8 2 - - -
Benthic - predators -27.0 ± 1.1 5.5 ± 0.3 3 -28.5 ± 1.7 4.2 ± 0.8 3 - - - - - -
Benthic - shredders -26.4 ± 0.2 3.0 ± 0.7 3 -27.9 ± 0.6 1.7 ± 1.0 3 -28.321 1.877 1 -29.6 ± 1.7 1.5 ± 0.7 3
Emergents - - - - - - - - - - - -
Terrestrial -25.6 ± 1.6 1.7 ± 2.0 2 -25.7 ± 0.2 3.2 ± 1.2 2 -27.8 ± 0.6 0.1 ± 1.2 2 -24.9 ± 0.6 3.0 ± 2.3 3
Fish
Rainbow trout - juveniles -25.0 ± 0.5 8.6 ± 0.0 2 - - - - - - - - -
Rainbow trout - adults - - - - - - - - - - - -
Chinook salmon - juveniles -23.5 ± 1.9 9.7 ± 1.1 6 - - - - - - - - -
Coho salmon - juveniles -23.2 ± 1.3 9.0 ± 1.5 8 - - - - - - - - -
Totals 53 32 20 28
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Table A3.4-10. Mean δ13C and δ15N ± SD for all sample types collected at FA 184 during spring sampling.
Spring Focus Area 184 Tributary Mouth (RP-184-1) Main Channel (RP-184-2) Side Channel (RP-184-3)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae
-28.7 ±
0.8
1.0 ±
0.5 3 -18.8 ± 4.2 3.9 ± 0.2 3 -16.5 ± 3.0 4.2 ± 0.1 3
Organic matter - drift
-27.4 ±
0.4
-3.9 ±
0.2 2 -26.5 ± 0.1
-2.0 ±
0.2 2 -26.4 ± 0.3 -2.7 ± 0.8 2
Organic matter - benthic
-28.2 ±
0.4
-3.3 ±
0.6 3 -26.5 ± 0.5
-3.4 ±
0.5 3 -26.5 ± 0.6 -4.7 ± 0.4 3
Salmon carcass - - - - - - - - -
Salmon eggs - - - - - - - - -
Invertebrates
Aquatic Invertebrates
-25.7 ±
1.5
0.8 ±
1.1 9 -27.8 ± 2.8 3.6 ± 2.1 6 -28.8 ± 2.4 2.9 ± 0.9 7
Benthic - collectors
-23.8 ±
0.4
-0.2 ±
0.3 3 -27.9 ± 0.4 1.7 ± 0.8 3 -28.0 ± 0.8 1.8 ± 0.4 2
Benthic - grazers
-27.2 ±
0.8
0.8 ±
0.7 3 - - - -29.4 ± 4.1 2.9 ± 0.4 3
Benthic - predators
-26.1 ±
0.4
1.9 ±
1.1 3 -27.7 ± 4.5 5.5 ± 0.3 3 -28.6 ± 0.2 4.1 ± 0.0 2
Benthic - shredders - - - - - - - - -
Emergents
-26.6 ±
0.8
1.3 ±
0.5 3 - - - -22.8 ± 0.6 1.7 ± 0.2 3
Terrestrial
-25.5 ±
0.5
1.8 ±
3.3 2 -24.8 ± 0.9
-2.6 ±
0.9 2 -25.7 ± 0.9 2.5 ± 2.0 2
Fish
Rainbow trout - juveniles - - - - - - - - -
Rainbow trout - adults - - - - - - - - -
Chinook salmon -
juveniles - - - - - - - - -
Coho salmon - juveniles - - - - - - - - -
Totals 31 22 27
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Table A3.4-11. Mean δ13C and δ15N ± SD for all sample types collected at FA 184 during summer sampling.
Summer Focus Area 184 Tributary Mouth (RP-184-1) Main Channel (RP-184-2) Side Channel (RP-184-3)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae
-21.8
± 2.2 1.9 ± 1.0 3 - - - -25.2 ± 1.7 2.8 ± 0.3 3
Organic matter - drift
-28.2
± 0.1
-4.2 ±
1.2 2 -27.1 ± 0.1 -3.9 ± 0.5 2 -26.7 ± 0.3 -4.7 ± 1.1 2
Organic matter - benthic
-27.9
± 0.5
-4.9 ±
0.4 3 -27.5 ± 0.6 -4.5 ± 0.2 3 -27.1 ± 0.1 -7.2 ± 1.1 3
Salmon carcass - - - - - - - - -
Salmon eggs - - - - - - - - -
Invertebrates
Aquatic Invertebrates
-26.9
± 1.9 0.5 ± 2.2
1
0 -25.3 ± 1.3 5.0 ± 2.8 3 -27.9 ± 0.1 2.1 ± 0.8 3
Benthic - collectors
-27.1
± 2.0 1.2 ± 0.2 3 -24.6 ± 0.8 5.4 ± 3.8 2 -27.9 ± 0.1 2.1 ± 0.8 3
Benthic - grazers
-27.5
± 2.8
-1.0 ±
1.8 3 - - - - - -
Benthic - predators
-26.3
± 1.7 2.7 ± 0.3 3 -26.7 4.2 1 - - -
Benthic - shredders -26.4 -3.4 1 - - - - - -
Emergents - - - - - - -25.9 ± 0.3 0.9 ± 0.4 3
Terrestrial
-25.4
± 0.8 3.0 ± 5.2 3 - - - -26.0 1.6 1
Fish
Rainbow trout - juveniles - - - - - - - - -
Rainbow trout - adults - - - - - - - - -
Chinook salmon -
juveniles - - - - - - - - -
Coho salmon - juveniles - - - - - - - - -
Totals 31 11 18
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Table A3.4-12. Mean δ13C and δ15N ± SD for all sample types collected at FA 184 during fall sampling.
Fall Focus Area 184 Tributary Mouth (RP-184-1) Main Channel (RP-184-2) Side Channel (RP-184-3)
Category Sample Type δ13C δ15N n δ13C δ15N n δ13C δ15N n
Endmembers
Benthic algae
-26.5
± 1.9
1.2 ±
0.6 3
-24.1 ±
1.1 3.5 ± 0.8 3 -24.2 ± 1.5 0.7 ± 0.4 3
Organic matter - drift
-28.9
± 0.3
-7.8 ±
0.7 2 -27.2 ± 0.1
-7.3 ±
0.5 2 -27.6 ± 0.6
-2.8 ±
1.6 2
Organic matter - benthic
-28.4
± 0.6
-7.2 ±
3.1 3 -27.6 ± 0.8
-5.8 ±
2.3 3 -27.0 ± 0.3
-3.7 ±
0.5 3
Salmon carcass - - - - - - - - -
Salmon eggs - - - - - - - - -
Invertebrates
Aquatic Invertebrates
-27.6
± 1.1
0.8 ±
0.7
1
1 -27.8 ± 1.6 2.0 ± 0.5 6 -28.4 ± 1.8 2.1 ± 1.1 4
Benthic - collectors
-26.8
± 0.6
0.3 ±
0.0 3 -29.2 ± 0.5 2.2 ± 0.3 3 -29.6 ± 2.2 2.1 ± 0.5 2
Benthic - grazers
-29.1
± 0.8
1.0 ±
0.3 3 -26.3 2.3 1 -27.2 3.5 1
Benthic - predators
-27.0
± 1.3
2.0 ±
0.9 2 -25.5 2.3 1 - - -
Benthic -
shredders
-27.1
± 0.3
0.3 ±
0.1 3 -27.6 0.9 1 -27.5 0.7 1
Emergents -27.3 2.8 1 - - - -26.3 ± 2.3 0.2 ± 1.7 3
Terrestrial - - - - - - - - -
Fish
Rainbow trout -
juveniles - - - - - - - - -
Rainbow trout - adults - - - - - - - - -
Chinook salmon -
juveniles - - - - - - - - -
Coho salmon - juveniles - - - - - - - - -
Totals 31 20 19
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Table A3.5-1. Diet composition of Chinook juveniles sampled by gastric lavage (proportions by dry mass). The isotopic origin of each prey category is indicated in parentheses.
Species / Life stage Season Focus Area Hab-itat
Mean diet mass (mg dry)
Diet proportions by dry mass
n (total) n (non-empty) Fish Eggs (Marine) Fish (Marine or Aquatic) Aquatic Inverts (Aquatic) Terrestrial Inverts (Aquatic) Terrestrial Inverts (Terrestrial)
Chinook Juv Spring RP-81 TM 8 8 2.1 - 0.70 0.07 0.23 -
US 8 7 0.3 - - 0.46 0.54 -
RP-104 SS 8 4 1.1 - - 0.91 0.09 -
RP-141 TM 8 6 45.5 - 0.96 0.00 0.00 0.04
Chinook Juv Summer RP-81 TM 1 1 0.4 - - - 1.00 -
RP-104 SC 8 6 7.9 0.55 0.27 0.04 - 0.15
SS 17 11 6.9 0.96 - 0.03 0.01 0.00
US 8 7 0.4 - - 0.82 0.18 -
RP-141 TM 5 5 8.8 0.86 - 0.10 0.03 -
US 8 7 0.8 0.25 - 0.03 0.73 0.00
Chinook Juv Fall RP-81 US 1 1 62.2 - - - - 1.00
RP-104 SC 3 2 1.5 0.65 - 0.12 0.23 -
SS 10 9 13.8 0.76 - 0.07 0.13 0.05
US 1 1 6.5 0.64 - 0.02 0.26 0.08
RP-141 TM 6 5 8.4 0.96 - 0.04 - -
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Table A3.5-2. Diet composition of coho juveniles sampled by gastric lavage (proportions by dry mass). The isotopic origin of each prey category is indicated in parentheses.
Species / Life stage Season Focus Area Hab-itat
Mean diet mass (mg dry)
Diet proportions by dry mass
n (total) n (non-empty) Fish Eggs (Marine) Fish (Marine or Aquatic) Aquatic Inverts (Aquatic) Terrestrial Inverts (Aquatic) Terrestrial Inverts (Terrestrial)
Coho Juv Spring RP-81 TM 9 7 0.3 - - 0.60 0.37 0.02
US 8 6 0.2 - - 0.49 0.34 0.17
RP-141 TM 8 3 0.6 - - 1.00 - -
Coho Juv Summer RP-81 TM 4 4 1.3 0.45 - 0.06 0.14 0.35
RP-104 SC 9 3 4.0 - - 0.11 - 0.89
SS 19 12 0.4 0.17 0.32 0.23 0.16 0.13
US 8 7 0.3 - - 0.93 0.07 -
RP-141 TM 8 8 10.8 0.96 - 0.04 0.00 -
US 3 3 0.4 - - 0.13 0.85 0.02
Coho Juv Fall RP-81 TM 2 2 15.3 0.96 - 0.03 0.01 -
US 4 2 1.5 - - 0.14 - 0.86
RP-104 SC 9 9 4.1 0.66 - 0.02 0.08 0.24
SS 16 14 6.3 0.85 - 0.04 0.03 0.08
US 5 4 0.2 - - 0.83 0.17 -
RP-141 TM 8 7 4.9 0.93 - 0.05 0.00 0.02
US 1 1 0.8 - - 0.12 0.88 0.00
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.5-3. Diet composition of rainbow trout adults and juveniles sampled by gastric lavage (proportions by dry mass). The isotopic origin of each prey category is indicated in parentheses.
Species / Life stage Season Focus Area Hab-itat
Mean diet mass (mg dry)
Diet proportions by dry mass
n (total) n (non-empty) Fish Eggs (Marine) Fish (Marine or Aquatic) Aquatic Inverts (Aquatic) Terrestrial Inverts (Aquatic) Terrestrial Inverts (Terrestrial)
Rainbow
Trout Adult Spring RP-104 SS 3 3 8.8 - - 0.64 - 0.36
RP-141 TM 1 1 79.5 - 0.98 0.02 0.00 -
Summer RP-104 SS 9 8 82.4 0.00 0.98 0.01 0.00 0.01
RP-141 TM 8 8 30.3 0.96 - 0.02 0.02 -
Fall RP-104 SS 8 7 47.9 1.00 - 0.00 - -
RP-141 TM 2 2 28.1 0.97 - 0.02 0.01 -
Rainbow
Trout Juv Spring RP-81 TM 9 6 0.1 - 0.15 0.25 0.60 -
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.6-1. Mean taxa richness and taxonomic richness estimates (n=3) from Hester-Dendy multiplate samplers collected in clear and warm water conditions in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week colonization period for the River Productivity Study.
Site
Turbidity/
Temperature Condition*
Sample
Set Depth
Days
Colonized
Density
(sq m)
Taxa Richness Avg (Total)
EPT Richness Avg (Total)
Mayfly (E) Taxa
Avg (Total)
Stonefly (P) Taxa
Avg (Total)
Caddisfly (T)Taxa
Avg (Total)
Chironomid Taxa Avg (Total)
Diversity
(H')
Evenness
(J')
RP-HD-1-5S CW Shallow 7 351.28 12 (20) 1.67 (3) 0 (0) 1.33 (2) 0.33 (1) 9.33 (14) 1.96 0.80
RP-HD-1-4S CW Shallow 15 271.79 14.67 (22) 2 (3) 0 (0) 1.33 (2) 0.67 (1) 11.33 (16) 2.40 0.90
RP-HD-1-3S CW Shallow 28 1794.36 24 (35) 1.67 (4) 0 (0) 0.67 (2) 1 (2) 17.67 (23) 2.54 0.80
RP-HD-1-2S CW Shallow 42 4757.24 34.5 (44) 3.5 (5) 0.5 (1) 0.5 (1) 2.5 (3) 23.5 (29) 2.74 0.77
RP-HD-1-1S CW Shallow 57 6670.02 35.33 (58) 5 (11) 1.67 (4) 1 (2) 2.33 (5) 21.67 (31) 2.67 0.75
RP-HD-1-5D CW Deep 7 164.10 10.67 (24) 1 (2) 0 (0) 0.67 (1) 0.33 (1) 7.33 (16) 2.05 0.94
RP-HD-1-4D CW Deep 15 620.51 24.33 (40) 4 (8) 0.67 (2) 1.33 (2) 2 (4) 16.67 (24) 2.82 0.88
RP-HD-1-3D CW Deep 28 3294.36 31.33 (51) 3.67 (6) 0.33 (1) 1.67 (2) 1.67 (3) 23 (33) 2.54 0.75
RP-HD-1-2D CW Deep 42 4139.68 30 (50) 2.33 (6) 0.67 (2) 0.33 (1) 1.33 (3) 22 (31) 2.57 0.76
RP-HD-1-1D CW Deep 57 6184.98 26.67 (42) 0.67 (2) 0.33 (1) 0 (0) 0.33 (1) 20 (29) 2.50 0.76
* CC=Clear & Cold; CW=Clear & Warm; TC=Turbid & Cold; TW=Turbid & Warm.
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.6-2. Mean taxa richness and taxonomic richness estimates (n=3) from Hester-Dendy multiplate samplers collected in clear and cold water conditions in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week colonization period for the River Productivity Study.
Site
Turbidity/
Temperature Condition*
Sample
Set Depth
Days
Colonized
Density
(sq m)
Taxa Richness Avg (Total)
EPT Richness Avg (Total)
Mayfly (E) Taxa
Avg (Total)
Stonefly (P) Taxa
Avg (Total)
Caddisfly (T)Taxa
Avg (Total)
Chironomid Taxa Avg (Total)
Diversity
(H')
Evenness
(J')
RP-HD-2-5S CC Shallow 7 158.97 8 (14) 0 (0) 0 (0) 0 (0) 0 (0) 7 (13) 1.83 0.88
RP-HD-2-4S CC Shallow 15 497.44 11 (19) 0.33 (1) 0 (0) 0.33 (1) 0 (0) 9.67 (17) 1.80 0.76
RP-HD-2-3S CC Shallow 28 1128.21 11 (17) 0 (0) 0 (0) 0 (0) 0 (0) 10 (16) 1.47 0.62
RP-HD-2-2S CC Shallow 42 3520.23 11.67 (18) 0 (0) 0 (0) 0 (0) 0 (0) 10.33 (16) 1.36 0.57
RP-HD-2-1S CC Shallow 57 3943.68 14.33 (23) 0.33 (1) 0 (0) 0 (0) 0.33 (1) 12.67 (20) 1.38 0.52
RP-HD-2-5D CC Deep 7 79.49 5.33 (10) 0 (0) 0 (0) 0 (0) 0 (0) 4.33 (9) 1.47 0.90
RP-HD-2-4D CC Deep 15 171.79 6.33 (12) 0 (0) 0 (0) 0 (0) 0 (0) 5 (9) 1.43 0.84
RP-HD-2-3D CC Deep 28 1828.21 12.67 (20) 0 (0) 0 (0) 0 (0) 0 (0) 10.67 (16) 1.52 0.60
RP-HD-2-2D CC Deep 42 1901.47 9.33 (13) 0.33 (1) 0 (0) 0 (0) 0.33 (1) 7.33 (9) 1.10 0.51
RP-HD-2-1D CC Deep 57 4370.60 12 (17) 0.33 (1) 0 (0) 0.33 (1) 0 (0) 10.33 (14) 1.41 0.57
* CC=Clear & Cold; CW=Clear & Warm; TC=Turbid & Cold; TW=Turbid & Warm.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 48 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.6-3. Mean taxa richness and taxonomic richness estimates (n=3) from Hester-Dendy multiplate samplers collected in turbid and cold water conditions in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week colonization period for the River Productivity Study.
Site
Turbidity/
Temperature Condition*
Sample
Set Depth
Days
Colonized
Density
(sq m)
Taxa Richness Avg (Total)
EPT Richness Avg (Total)
Mayfly (E) Taxa
Avg (Total)
Stonefly (P) Taxa
Avg (Total)
Caddisfly (T)Taxa
Avg (Total)
Chironomid Taxa Avg (Total)
Diversity
(H')
Evenness
(J')
RP-HD-3-4S TC Shallow 8 2.56 0.33 (1) 0 (0) 0 (0) 0 (0) 0 (0) 0.33 (1) 0.00 0.00
RP-HD-3-3S TC Shallow 21 94.87 6 (12) 0.67 (1) 0 (0) 0 (0) 0.67 (1) 3.67 (8) 1.62 0.92
RP-HD-3-2S TC Shallow 35 94.87 5 (10) 0.67 (1) 0 (0) 0.67 (1) 0 (0) 3.33 (7) 0.99 0.52
RP-HD-3-1S TC Shallow 49 28.21 1.67 (3) 0 (0) 0 (0) 0 (0) 0 (0) 0.67 (2) 0.33 0.48
RP-HD-3-4D TC Deep 8 17.95 2.33 (6) 0.33 (1) 0 (0) 0 (0) 0.33 (1) 0.67 (2) 0.73 0.00
RP-HD-3-3D TC Deep 21 69.23 4.33 (8) 0.67 (1) 0 (0) 0 (0) 0.67 (1) 2.33 (4) 1.27 0.91
RP-HD-3-2D TC Deep 35 48.72 3.33 (7) 0.67 (2) 0 (0) 0.33 (1) 0.33 (1) 1.33 (3) 1.01 0.85
RP-HD-3-1D TC Deep 49 171.79 7.33 (14) 2.33 (4) 0.33 (1) 1.33 (2) 0.67 (1) 3 (6) 1.60 0.80
* CC=Clear & Cold; CW=Clear & Warm; TC=Turbid & Cold; TW=Turbid & Warm.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 49 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Table A3.6-4. Mean taxa richness and taxonomic richness estimates (n=3) from Hester-Dendy multiplate samplers collected in turbid and warm water conditions in the Whiskers Slough Focus Area (FA-104) during August and September 2013 for an 8-week colonization period for the River Productivity Study.
Site
Turbidity/
Temperature Condition*
Sample
Set Depth
Days
Colonized
Density
(sq m)
Taxa Richness Avg (Total)
EPT Richness Avg (Total)
Mayfly (E) Taxa
Avg (Total)
Stonefly (P) Taxa
Avg (Total)
Caddisfly (T)Taxa
Avg (Total)
Chironomid Taxa Avg (Total)
Diversity
(H')
Evenness
(J')
RP-HD-4-4S TW Shallow 9 20.51 2.33 (6) 0.33 (1) 0 (0) 0.33 (1) 0 (0) 1.67 (4) 0.67 0.64
RP-HD-4-3S TW Shallow 22 2.56 0.33 (1) 0.33 (1) 0 (0) 0.33 (1) 0 (0) 0 (0) 0.00 0.00
RP-HD-4-2S TW Shallow 36 156.41 7 (14) 2.33 (5) 0.67 (2) 1 (2) 0.67 (1) 4.67 (9) 1.46 0.77
RP-HD-4-1S TW Shallow 50 30.77 2.33 (5) 0 (0) 0 (0) 0 (0) 0 (0) 2.33 (5) 0.63 0.62
RP-HD-4-4D TW Deep 9 194.87 7 (14) 1 (2) 0 (0) 0.67 (1) 0.33 (1) 5.67 (11) 1.44 0.74
RP-HD-4-3D TW Deep 22 343.59 6.67 (10) 2.67 (4) 0.67 (1) 1.33 (2) 0.67 (1) 3.67 (5) 1.33 0.70
RP-HD-4-2D TW Deep 36 623.08 10 (20) 2.67 (5) 0.67 (1) 1.33 (2) 0.67 (2) 6.67 (13) 1.28 0.55
RP-HD-4-1D TW Deep 50 758.97 12 (21) 3 (5) 1 (2) 1.33 (2) 0.67 (1) 9 (16) 1.70 0.69
* CC=Clear & Cold; CW=Clear & Warm; TC=Turbid & Cold; TW=Turbid & War
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
FIGURES
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FERC Project No. 14241 Appendix A - Page 51 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Figure A3.4-1. δ15N vs. δ13C bi-plot for all juvenile Chinook salmon samples collected at each site (marker shapes) and across all seasons (marker colors) with average freshwater, terrestrial, and marine diet sources shown in black.
?
?
?
?
?
?
?
?
? ?
?
?
?
?
Freshw ater
Mar ine
T errestr ial
2.5
5.0
7.5
10.0
12.5
?35 ?30 ?25 ?20
δ 13 C (%) δ 1 5 N (%) ? 104 SC
104 SS
104 TM
104 US
141 TM
81 TM
81 US
Fall
Spring
Summer
?
?
?
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Figure A3.4-2. δ15N vs. δ13C bi-plot for all juvenile coho salmon samples collected at each site (marker shapes) and across all seasons (marker colors) with average freshwater, terrestrial, and marine diet sources shown in black.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 53 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Figure A3.4-3. δ15N vs. δ13C bi-plot for all juvenile rainbow trout samples collected at each site (marker shapes) and across all seasons (marker colors) with average freshwater, terrestrial, and marine diet sources shown in black.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 54 September 2014
TECHNICAL MEMORANDUM RIVER PRODUCTIVITY STUDY 2013 INITIAL RESULTS
Figure A3.4-4. δ15N vs. δ13C bi-plot for all adult rainbow trout samples collected at each site (marker shapes) and across all seasons (marker colors) with average freshwater, terrestrial, and marine diet sources shown in black.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix A - Page 55 September 2014