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

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)

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

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

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

Cache Slough and Tributary Locations in CA

Cache Slough Sample Sites

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

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

Cache Slough Sampling

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.

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

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 31 - 97 35 - 99 Mean = 1.3 Mean = 1.1 Mean = 75.5 Mean = 83.7

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

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

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 1.1 -3.9 Fall 2012 10 1.3 – 2.8 Fall 2013 5 1.2 – 3.0

Sum of Pyrethroid Toxic Units (TUs) Based on Hyalella from Spring and Fall 2012 (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

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

Sum of Pyrethroid Toxic Units (TUs) Based on Hyalella from Spring and Fall 2013 (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

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

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

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%

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

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

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

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

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

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

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

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.

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

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

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

Pyrethroid Spring – Range Fall – Range Bifenthrin 0.2 – 3.8 0.3 – 1.5 Range of Cache Slough Sediment Pyrethroid Concentrations (ng/g @ 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

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%

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%

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

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

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