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Patterns and Trends in Sediment Toxicity in the San Francisco Estuary Brian Anderson, Bryn Phillips, John Hunt University of California, Davis Bruce Thompson,

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Presentation on theme: "Patterns and Trends in Sediment Toxicity in the San Francisco Estuary Brian Anderson, Bryn Phillips, John Hunt University of California, Davis Bruce Thompson,"— Presentation transcript:

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

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

5 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: Tests used are those recommended for evaluating compliance with proposed statewide SQOs

6 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

7 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%

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

9 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 2004 Benthic impact 100% stations

10 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

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

12 Mortality (%) Grizzly Bay Sediment-Water Interface TIE w/ EDTA 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) 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 ) Toxicity is probably not due to organic chemicals Sediment is toxic, pore water is not Toxicity is due to some acid-soluble compound

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

15 Results of NOAA/EMAP studies A. abdita1981.5% – E. estuarius4867% A. punctulata embryo develop.*19982% A. punctulata fertilization*19932% 0.8 – 3.86 *Tested using 100% porewater n % Toxic SQGQ1 TOC Grain Size

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?


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