Patterns and Trends in Sediment Toxicity in the San Francisco Estuary

Brian Anderson, Bryn Phillips, John HuntUniversity of California, Davis

Bruce Thompson, Sarah LoweSan Francisco Estuary Institute

Karen Taberski California Regional Water Quality Control Board – San Francisco Bay Region

R. Scott CarrUSGS Corpus Christi

Contaminants entering the estuary attach to particles which may then be deposited

as sediments

Contaminants may impact benthicorganisms or higher trophic level

species

Amphipod 10-d survival test

Laboratory Toxicity Testing(UC Davis – MarinePollution Studies Lab)

Measures acute effects

Mussel embryo development

48-h exposureSublethal 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:

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

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Rivers

Grizzly BayNapa RiverSan Pablo Bay

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South Bay

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Redwood Creek

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Yerba Buena Island

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Horseshoe Bay

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100%Coyote Creek

San Jose

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Legend:

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Sampling Period (1993 to 2001)

Amph % Survival Biv % Norm. Dev. 

Some stations are consistently toxic, others exhibit seasonal toxicity

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)

Winter Summer0

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1001993-2000

% S

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18%

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0.06 0.20 0.40 0.60 0.80 1.00 1.40

toxic nontoxic

Never Toxic Always Toxic

r = - 0.685p = <0.0001n = 118

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ipod

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ival

mERMQ

Amphipod response vs. contaminant mixtures

Thompson et el. 1999

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0.06 0.20 0.40 0.60 0.80 1.00 1.40

toxic nontoxic

Never Toxic Always Toxic

r = - 0.685p = <0.0001n = 118

Am

ph

ipod

% s

urv

ival

mERMQ

Amphipod response vs. contaminant mixtures

Benthic impact68% stations

Thompson et el. 1999Thompson and Lowe 2004

Benthic impact100% stations

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

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Grizzly Bay Bivalve TIE w/ 25% Elutriate

Phillips et al. 2003

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Control Controlw/EDTA

Site Sitew/EDTA

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Grizzly BaySediment-Water Interface TIE w/ EDTA

Phillips et al. 2003

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. 2005)

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

Results of NOAA/EMAP studies 2000-2001

A. abdita 198 1.5% 0.46 - 8.82 2.94 – 96.55

E. estuarius 48 67%

A. punctulata embryo develop.* 199 82%

A. punctulata fertilization* 199 32%

0.8 – 3.86

*Tested using 100% porewater

n%

ToxicSQGQ1 TOC Grain Size

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

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

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?