1. Potential Influence of Pyrethroids, Metals, Sediment Characteristics, and Water Quality Conditions on Benthic Communities in Cache Slough
Lenwood Hall
William Killen
Ronald Anderson
University of Maryland
Wye Research and Education Center
Queenstown, Maryland
and
Raymond Alden III
Northern Illinois University

2. Background
Cache Slough is ~ 18 km in length and is located in the northwest Delta area of CA
Other investigators have recently reported potentially toxic water concentrations of pyrethroids in the Cache Slough area
It is an important spawning and nursery area for Delta Smelt and other important fish species (Longfin Smelt, Sacramento Splittail, Chinook Salmon)

3. Key Fish Species in Cache Slough
Delta Smelt
Sacramento Splittail
Longfin Smelt
Chinook Salmon

4. Objectives
Collect and identify benthic macroinvertebrates (BMIs) from 12 sites in the Cache Slough area in the spring and fall of 2012 and 2013
Measure pyrethroids , total organic carbon (TOC), grain size, total metals and SEM/AVS in sediment from all sites where benthic organisms are collected
Measure basic water quality parameters at each site
Use univariate regressions and stepwise multiple regressions to determine relationship between benthic metrics and pyrethroids, metals, TOC and grain size

5. Value of Study
Sediment concentrations of pyrethroids will provide perspective to water column concentrations previously reported in the Cache Slough area
Benthic sampling will provide new benthic data for this waterbody
Sediment metals data for the study area will provide new information not currently available
BMI data from this study area would be useful for the Biological Objectives Process in California

6. Cache Slough and Tributary Locations in CA

7. Cache Slough Sample Sites

8. Study Design 12 sites were sampled during the spring and fall of 2012
Sites were selected based on a reconnaissance sampling trip in advance of spring sampling
Different types of habitat were a criterion in the site selection process
Confluence points from various water bodies were considered in the site selection process
Non-wadeable water body that was sampled by boat

9. Study Design Depth ranges from 1.5 to 9 m depending on tidal cycle
Benthic communities were sampled from 5 randomly selected locations along a 100 m transect and the sample was composited
Sediment samples were collected using a petite ponar (2-3 cm)
Benthic ID work was conducted by CDFG
Pyrethroids, metals, TOC, grain size were measured on the same sample used for BMIs

10. Cache Slough Sampling

11. Study Design
Basic water quality was measured at each site (temperatue, pH, salinity, conductivity, DO, and turbidity)
Univariate regressions and stepwise multiple regressions analysis were used to determine relationships between various benthic metrics and (a) pyrethroids; (b) metals (bulk metals and SEM/AVS); (c) grain size; and (d) TOC.

12. Ranges of Cache Slough Water Quality Parameters for 2012 and 2013
Spring
Fall
Temp (C)
12.0 – 16.9
16.2 – 19.1 pH
6.98 – 8.2
7.5 – 8.4
D. O. (mg/L)
7.34 – 10.7
7.2 – 10.0
Cond (uS)
110 – 605
125 – 559
Sal (ppt)
0.1 – 0.4
0.1 – 0.3
Turb (NTU)
6- 255
4.6 – 74

13. Ranges and Mean TOC and Grain Size Values for 12 Cache Slough Sites Sampled in Spring and Fall of 2012 and 2013
% TOC
% Silt/Clay
Spring
Fall
0.6 – 4.4
0.7 – 1.7
Mean = 1.3
Mean = 1.1
Mean = 75.5
Mean = 83.7

14. Number of Metals TEL Exceedances by Metal and Season for Cache Slough sites in 2012 and 2013 (24 values)
Metal
Spring
Fall
TEL (ug/g dw) As 15 13
5.9 Cd 3
.596 Cr 21 23
37.3 Cu 19
35.7 Pb 35 Hg 5 4
.174 Ni 24 18 Zn 1
123.1

15. Natural Sources of Cr, Ni, As and Cu in Cache Slough
Discussions with geologists at UC Davis (Peter Green, Randal Southard) and CA Geological Survey (Ron Churchill)
Serpentine soils in Solano County area near Cache Slough
Serpentine soils are naturally high in Cr and Ni (Bonifacio et al. 2010)
Arsenic (2.1 – 13.8 ug/g) and copper (6.3 – 62 ug/g) in Solano county soils are similar to range reported in sediment

16. Number of SEM/AVS Ratios > 1 with at least one metal exceeding a TEL for Cache Slough sites by season in 2012 and 2013 (12 sites per season)
Season/Year
# SEM/AVS Ratios >1
Range SEM/AVS Ratios
Spring 2012 8
1.4 – 9.8
Spring 2013 7
Fall 2012 10
1.3 – 2.8
Fall 2013 5
1.2 – 3.0

17. Sum of Pyrethroid Toxic Units (TUs) Based on Hyalella from Spring and Fall (values > 1 in yellow)
Sum of Pyrethroid TUs
Station
Spring
Fall
CS-1
0.31
0.14
CS-2
0.15
0.13
CS-3
0.25
0.12
CS-4
0.05
0.07
CS-5
0.16
0.11
CS-6
CS-7
0.35
0.28
CS-8
1.97
0.49
CS-9
1.39
0.26
CS-10
1.07
0.27
CS-11
1.24
0.33
CS-12
0.29

18. Sum of Pyrethroid Toxic Units (TUs) Based on Chironomus from Spring and Fall 2012
Sum of Pyrethroid TUs
Station
Spring
Fall
CS-1
0.023
0.080
CS-2
0.010
0.005
CS-3
0.020
CS-4
0.001
0.004
CS-5
0.008
CS-6
0.019
CS-7
0.015
0.027
CS-8
0.139
0.050
CS-9
0.127
0.014
CS-10
0.102
CS-11
0.114
0.021
CS-12
0.018

19. Sum of Pyrethroid Toxic Units (TUs) Based on Hyalella from Spring and Fall (values > 1 in yellow)
Sum of Pyrethroid TUs
Station
Spring
Fall
CS-1
0.25
0.10
CS-2
0.15
0.06
CS-3
0.27
0.09
CS-4
0.26
CS-5
0.13
CS-6
0.14
CS-7
0.35
CS-8
CS-9
0.17
CS-10
0.41
CS-11
0.36
CS-12
0.22
0.16

20. Spring Benthic Community Results from 2012 and 2013
54 to 56 benthic taxa collected at 12 sites during each year
The 5 most dominant taxa – comprising 74 to 79% of the total # individuals – were all considered tolerant or moderately tolerant of general water quality stressors
The most dominant taxa collected was the amphipod (Americorophium) – 25 to 33% of the total # of individuals

21. Fall Benthic Community Results from 2012 and 2013
43 to 44 benthic taxa collected at 12 sites
The 5 most dominant taxa – comprising 76 – 85 % of the total # individuals – were all considered tolerant or moderately tolerant
The most dominant taxa collected was the amphipod (Americorophium) – 28 to 37 % of the total # of individuals

22. Five Dominant BMI Taxa Collected in Cache Slough 2012 - 2013
Manayunkiia speciosa
18.96%
Americorophium
30.84%
Unid immature Tubificidae
11.50%
Chironomus
8.15%
Corbicula
7.54%

23. Benthic Metrics Used for Stepwise Multiple
Linear Regression and Response to Impairment
Benthic Metric
Response to Impairment
# Collector/Filterer & Collector/Gatherer
Increase
Abundance
Decrease
% Amphipoda
Variable
% Collector/Filterer & Collector/Gatherer
% Corbicula
% Dominant Taxa
% Oligochaeta
% Predators
% Tolerant Taxa
Shannon Diversity
Taxa Richness

24. Significant Variables % Coll/Filt & Coll/Gath
Results of stepwise multiple linear regression models of benthic metrics versus TUs for pyrethroids, sediment characteristics and metals to TEL ratios for Cache Slough in 2012 and 2013
Benthic Metrics
Significant Variables
% Coll/Filt & Coll/Gath
+ As
Abundance
- % TOC, - % Silt

25. Conclusions
Sediment sites selected from a random process were dominated by fine grain material (silt and clay)
There were a number of metals TEL exceedances for the four sampling periods with the highest number of exceedences for Cr and Ni
The sum of pyrethroid TUs based on Hyalella exceeded 1 at four sites during the spring of 2012 but all TUs were less than 1 during the other three sampling periods

26. Conclusions
The sum of pyrethroid TUs based on Chironomus were considerably less than 1 for all sampling periods
Fifty-four to 56 benthic taxa were reported during the spring while 43 to 44 benthic taxa were reported during the fall

27. Conclusions
The benthic metric % Collector/Filterer & Collector/Gatherer displayed a direct relationship with As based on the 2 year data set
Based on the multiple year data set, the benthic metric abundance was inversely related to % TOC and % Silt thus suggesting that the number of benthic organisms increased in coarser, less organic-rich sediments

28. Conclusions
Additional data are needed to confirm the significant patterns, as well as potentially detect other relationships that may be present between benthic metrics and environmental stressors

30. Conclusions
The benthic metric % Collector/Filterer & Collector/Gatherer displayed a direct relationship with As and an inverse relationship with % silt
The benthic metric abundance was inversely related to TOC
Samples with higher sand content had a higher percentage of collectors/filterers, collectors/gatherers and taxonomic diversity

31. Conclusions
Sediment characteristics and not pyrethroids or metals were the most important factor determining benthic community composition in Cache Slough based on a single year of data.

33. Bulk Metals Concentrations in Sediment (µg/g dw) for the 12 Cache Slough Sites Sampled in 2012 (metals concentrations exceeding Threshold Effects Levels (TELs) are in yellow) As Cd Cr Cu
Station
Spr
Fall
CS-1
6.47
5.61
0.404
0.637
54.8
64.4
42.3
40.9
CS-2
5.55
6.67
0.322
0.630
52.8
68.2
36.5
45.8
CS-3
4.75
3.95
0.338
0.381
46.9
56.8
33.7
34.7
CS-4
7.99
6.90
0.499
0.359
63.3
64.8
51.5
42.6
CS-5
5.68
7.21
0.353
0.466
58.4
81.4
42.2
54.6
CS-6
7.11
8.45
0.337
0.432
64.9
89.3
47.5
60.0
CS-7
7.00
8.56
0.211
0.262
49.5
62.6
45.4
50.2
CS-8
6.79
6.48
0.201
0.200
48.3
51.9
47.1
44.4
CS-9
6.44
5.65
0.192
0.165
46.2
49.6
36.7
CS-10
4.03
4.34
0.104
0.099
30.5
35.5
25.4
21.7
CS-11
5.06
4.68
0.157
0.174
41.1
38.0
39.1
CS-12
1.83
4.15
0.092
0.210
19.8
53.2
20.2
47.8
TEL
5.9
0.596
37.3
35.7

34. Bulk Metals Concentrations in Sediment (µg/g dw) for the 12 Cache Slough Sites Sampled in 2012 (metals concentrations exceeding Threshold Effects Levels (TELs) are in yellow) Pb Hg Ni Zn
Station
Spr
Fall
CS-1
8.27
7.82
0.061
0.107
73.2
86.0
95.3
105
CS-2
7.07
9.14
0.047
0.117
73.6
85.6
83.7
100
CS-3
6.49
6.42
0.080
0.122
63.4
74.6
79.5
92.1
CS-4
9.80
8.82
0.180
0.174
83.6
90.5
CS-5
17.6
11.0
0.182
84.2
107
89.8
117
CS-6
8.99
11.7
0.097
0.203
91.6
114
92.9
CS-7
10.3
12.4
0.031
0.183
72.9
83.3
98.4
111
CS-8
12.8
11.2 ND
0.106
75.4
72.1
119
106
CS-9
11.8
10.4
0.067
0.093
69.0
67.5
90.1
CS-10
6.98
7.63
0.075
0.056
41.8
51.9
65.6
62.4
CS-11
10.6
10.5
0.071
0.088
60.0
66.4
96.5
97.9
CS-12
4.74
11.4
0.119
0.148
30.0
74.4
42.0
99.1
TEL 35 18
123.1

35. SEM/AVS ratios from Spring and Fall of 2012 (yellow SEM/AVS ratios > 1 suggest metals are bioavailable and may be toxic if at least one metal exceeds a TEL)
SEM/AVS
Station
Spring
Fall
CS-1
9.60
2.17
CS-2
0.70
1.35
CS-3
8.60
1.79
CS-4
12.5
2.77
CS-5
9.80
2.71
CS-6
4.20
1.78
CS-7
5.00
2.60
CS-8
0.76
2.68
CS-9
1.40
2.33
CS-10
0.51
1.63
CS-11
0.23
0.94
CS-12
5.90
0.89

36. Pyrethroid Spring – Range Fall – Range Bifenthrin 0.2 – 3.8 0.3 – 1.5
Range of Cache Slough Sediment Pyrethroid Concentrations 1% TOC) by Season in 2012
Pyrethroid
Spring – Range
Fall – Range
Bifenthrin
0.2 – 3.8
0.3 – 1.5
Fenpropathrin
ND – 0.009
ND – 0.007
Lambda-cyhal
0.05 – 4.6
0.04 – 0.65
Permethrin
ND – 0.59
0.04 – 0.71
Cyfluthrin
ND – 0.57
ND – 0.43
Cypermethrin
0.02 – 0.50
ND – 0.045
Esfenvalerate
0.05 – 0.30
0.02 – 0.057
Deltamethrin
ND – 0.44
ND – 0.18

37. Five Dominant BMI Taxa Collected in Cache Slough During Spring 2012
Manayunkiia speciosa
15.5%
Americorophium
stimpsoni
25.0%
Unid immature Tubificidae
14.1%
Chironomus
10.9%
Corbicula
8.7%

38. Five Dominant BMI Taxa Collected in Cache Slough During Fall 2012
Americorophium
stimpsoni
27.7%
Unid immature Tubificidae
14%
Chironomus
13.5%
Manayunkiia speciosa 9%
Tryonia
12.2%

39. Results of ANOVA models of benthic metrics versus season, region and interaction of season and region
Metric
Season
Region
Season x Region
Taxonomic Richness NS
% Dominant Taxon
Shannon Diversity
Amphipods
Corbicula
Oligochaetes
% Predators
% Tolerant Taxa (8-10)
# Collector/Filterer & Collector/Gatherer
% Collector/Filterer & Collector/Gatherer
Abundance (#/sample)
L > M and U

40. Significant Variables # Coll/Filt & Coll/Gath % Coll/Filt & Coll/Gath
Results of stepwise multiple linear regression models of benthic metrics versus TUs for pyrethroids, sediment characteristics and metals to TEL ratios for Cache Slough in 2012 (NS = Not Significant)
Benthic Metrics
Significant Variables
Taxonomic Richness NS
% Dominant Taxa
Shannon Diversity
Amphipods
Corbicula
Oligochaetes
% Predators
% Tolerant Taxa
# Coll/Filt & Coll/Gath
% Coll/Filt & Coll/Gath
+ As to TEL; - Silt
Abundance
- TOC

41. Canonical Correlation Analysis of Benthic Versus Environmental Data for Cache Slough in 2012 (r2 = 0.54)
R2 = 0.54
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