Patterns and Trends in Sediment Toxicity in the San Francisco Estuary

1. Patterns and Trends in Sediment Toxicity in the San Francisco Estuary Brian Anderson, Bryn Phillips, John Hunt University of California, Davis Bruce Thompson, Sarah Lowe San Francisco Estuary Institute Karen Taberski California Regional Water Quality Control Board – San Francisco Bay Region R. Scott Carr USGS Corpus Christi

2. Contaminants entering the estuary attach to particles which may then be deposited as sediments Contaminants may impact benthic organisms or higher trophic level species

3. Laboratory Toxicity Testing (UC Davis – Marine Pollution Studies Lab) Amphipod 10-d survival test Measures acute effects

4. Mussel embryo development 48-h exposure Sublethal endpoint Sediment elutriate exposure Sediment-water interface exposure

5. Sediment Quality Triad Toxicity test data used in a weight-of-evidence: Tests used are those recommended for evaluating compliance with proposed statewide SQOs Sediment contamination Sediment toxicity Benthic community structure Bioaccumulation Results used to identify and map areas of impaired or potentially impaired beneficial uses: Aquatic life Human health Wildlife

6. Napa River Legend: Grizzly Bay San Pablo Bay Rivers Horseshoe Bay Yerba Buena Island Redwood Creek San Jose Coyote Creek South Bay Some stations are consistently toxic, others exhibit seasonal toxicity

7. 1993-2000 100 % Stations toxic to amphipods 50 36% 10% 0 Winter Summer Change in RMP Experimental Design: 1993 –2001: Winter and Summer Sampling of Fixed Stations 2002-2003: Summer Sampling Using Probabilistic Sampling Design (7 fixed stations + 21 random stations) 2002 100 % Stations toxic to amphipods 50 18% 0 Summer

8. Amphipod response vs. contaminant mixtures 100 80 r = - 0.685 p = <0.0001 60 n = 118 Amphipod % survival 40 20 0 0.06 0.20 0.40 0.60 0.80 1.00 1.40 mERMQ Always Toxic Never Toxic toxic nontoxic Thompson et el. 1999

9. Amphipod response vs. contaminant mixtures toxic nontoxic 100 80 r = - 0.685 p = <0.0001 60 n = 118 Amphipod % survival 40 20 0 0.06 0.20 0.40 0.60 0.80 1.00 1.40 mERMQ Always Toxic Never Toxic Benthic impact 68% stations Benthic impact 100% stations Thompson et el. 1999 Thompson and Lowe 2004

10. Toxicity Identification Evaluations (TIEs) Phase I – characterization: e.g., metals vs organics, ammonia, H2S Phase II – identification: specific metal or organic compound(s) responsible for toxicity Phase III – confirmation Consider confounding factors: grain size, ammonia, pH etc. Once identified, chemical responsible for toxicity are emphasized in later studies : Source identification and control

11. Grizzly Bay Bivalve TIE w/ 25% Elutriate Mortality (%) Phillips et al. 2003

12. Grizzly Bay Sediment-Water Interface TIE w/ EDTA Mortality (%) Phillips et al. 2003

13. Bivalve TIEs Summary: • Copper is implicated as the primary cause of sediment toxicity to bivalves in Grizzly Bay samples (elutriates, sediment-water interface) • u Divalent metals cause elutriate toxicity at the majority of stations where elutriate TIEs have been conducted • Amphipod TIE Summary: Grizzly Bay (in Hunt et al. 2005) • Toxicity is probably not due to organic chemicals • Sediment is toxic, pore water is not • Toxicity is due to some acid-soluble compound

14. North Bay Rivers Napa River Petaluma River Coyote Creek Redwood Creek Guadalupe River

15. Results of NOAA/EMAP studies 2000-2001 % Toxic Grain Size TOC SQGQ1 n 2.94 – 96.55 0.8 – 3.86 A. abdita 198 1.5% 0.46 - 8.82 E. estuarius 48 67% A. punctulata embryo develop.* 199 82% A. punctulata fertilization* 199 32% *Tested using 100% porewater

16. Water Column Toxicity • Toxicity of water has been assessed with mysid shrimp and larval fish • Reductions in water column toxicity is apparently associated with reduced applications of OP pesticides • Previous evidence suggests toxicity is greatest during storm events • Water column toxicity is now assessed every 5 years in summer sampling at selected Status and Trends stations • This design does not address winter stormwater toxicity at the margins of the Estuary

17. Proposed Future Work: Sediment Toxicity • Continued Status and Trends monitoring • Application of TIEs at stations consistently toxic to amphipods • Emphasize winter sampling at the mouths of key tributaries • Proposed Special Studies • Gradient studies to link sediment toxicity with benthic community impacts – validation of sediment quality objectives • Dose-response toxicity tests with resident and surrogate toxicity test species – this work is now being conducted

18. Proposed Future Work: Water Toxicity • Continued Status and Trends monitoring on 5 yr cycle • Emphasize winter sampling at the mouths of key tributaries (incorporate chronic endpoints) • Synoptic sampling with sediment toxicity special studies?