Summary of 10 years of sediment toxicity monitoring for the San Francisco Estuary Regional Monitoring Program Brian Anderson, Bryn Phillips, John Hunt, Patricia Nicely, Ron Tjeerdema University of California, Davis Bruce Thompson, Sarah Lowe, Jay Davis San Francisco Estuary Institute Karen Taberski California Regional Water Quality Control Board – San Francisco Bay Region

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

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

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

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 Sediment Quality Triad Toxicity test data used in a weight-of-evidence

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

Change in RMP Experimental Design: 1993 –2001: Winter and Summer Sampling of Fixed Stations : Summer Sampling Using Probabilistic Sampling Design (7 fixed stations + 21 random stations) WinterSummer % Stations toxic to amphipods 36% 10% Summer % Stations toxic to amphipods 18%

toxic nontoxic Never Toxic Always Toxic r = p = < n = 118 Amphipod % survival mERMQ Amphipod response vs. contaminant mixtures Thompson et el. 1999

toxic nontoxic Never Toxic Always Toxic r = p = < n = 118 Amphipod % survival mERMQ Amphipod response vs. contaminant mixtures Benthic impact 68% stations Thompson et el Thompson and Lowe in review Benthic impact 100% stations

Toxicity Identification Evaluations (TIEs) Phase I – characterization: e.g., metals vs organics, ammonia, H 2 S 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

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

Mortality (%) Sediment-Water Interface TIE w/ EDTA Phillips et al. in press

Bivalve TIE Summary: Grizzly Bay Copper is implicated as the primary cause of sediment toxicity to bivalves (elutriates, sediment-water interface) Other divalent metals may also contribute to elutriate toxicity Amphipod TIE Summary: Grizzly Bay Toxicity is probably not due to organic chemicals Sediment is toxic, pore water is not Toxicity is due to some acid-soluble compound

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

Future Work Continued Status and Trends monitoring Application of TIEs at consistently toxic stations Winter samples Possible Special Studies Winter sampling at the base of key tributary streams Dose-response toxicity tests with resident and surrogate toxicity test species