Draft Data - Do not cite or quote Spatial and temporal patterns in food web accumulation of Hg EEPS Five Year Workplan Presentation to Exposure and Effects Work Group

Draft Data - Do not cite or quote Talk outline Review workplan Results update Questions for EEWG and Science Advisory Panel – –Questions on small fish work – –Other potential studies

Draft Data - Do not cite or quote Five Year Workplan: Specific questions to address Where is mercury entering the Bay food web? What habitats, conditions, or factors help to identify hotspots of food web accumulation in Bay margins? Are there interannual trends in MeHg bioaccumulation resulting from wetland and margin restoration activities? What are the best biomonitoring tools for characterizing hotspots of MeHg bioaccumulation?

Draft Data - Do not cite or quote Approach: Hg in small fish Annual monitoring at 10 stations to determine trends Spatial survey of about 40 stations Comparison of biosentinel tools (pending first year results) – –Fish vs. bivalves vs. sediment vs. diffusive gradient thinfilm devices

Draft Data - Do not cite or quote Annual monitoring of trend stations

Draft Data - Do not cite or quote Trend Sampling Locations Alviso Slough Newark Slough Bird Island/ Steinberger Slough Eden Landing China Camp Benicia Park Control Impact (Restoration) Point Isabel Candlestick Point Hamilton Oakland Middle Harbor

Draft Data - Do not cite or quote Trend analysis – a multiple station BACI design

Draft Data - Do not cite or quote Spatial survey Targeting 40 locations Targeting 40 locations Multiple interrelated factors Multiple interrelated factors A.Land use, land cover, and Hg sources B.Spatial location in Bay C.Subtidal hydrology and bathymetry D.Sediment physical and chemical parameters

Draft Data - Do not cite or quote Results update Preliminary results from 2005 and 2006 Spatial patterns Spatial patterns Interannual trends Interannual trends Focusing on topsmelt and Mississippi silverside (most complete spatial coverage) Focusing on topsmelt and Mississippi silverside (most complete spatial coverage)

Draft Data - Do not cite or quote Hg wet weight ( g/g) 2005 elevated in southern stations (significant) 2005 elevated in southern stations (significant) 2006 elevated in Pt. Isabel (significant) 2006 elevated in Pt. Isabel (significant) Spatial patterns

Draft Data - Do not cite or quote 2005 elevated in southern stations (not significant) 2005 elevated in southern stations (not significant) 2006 elevated in southern stations, Pt. Isabel, and Tiburon (significant) 2006 elevated in southern stations, Pt. Isabel, and Tiburon (significant)

Draft Data - Do not cite or quote Potential explanations for spatial patterns: Potential explanations for spatial patterns: –High sediment MeHg in southern stations, Tiburon –Suggests linkage: fish vs. sediment MeHg –Suggests spatial gradient Source: RMP

Draft Data - Do not cite or quote Station effect Year effect Interaction term Interannual trends Mississippi silverside

Draft Data - Do not cite or quote Station effect

Draft Data - Do not cite or quote Year effect and interaction 2006 generally lower than 2005

Draft Data - Do not cite or quote Station effect Year effect 2006 higher than 2005! Interannual trends Topsmelt

Draft Data - Do not cite or quote Results update summary Ability to detect significant spatial variation Ability to detect significant spatial variation –South Bay, Tiburon, Pt. Isabel appear elevated Substantial interannual variation Substantial interannual variation –Topsmelt and silverside seeing different MeHg signals –Subtle treatment effects likely missed Biosentinels sensitive to changes Biosentinels sensitive to changes

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Questions to Advisory Panel Design considerations 1. Habitat types: Bay margins vs. wetlands and salt ponds 2. Design – probabilistic vs. gradients and factors 3. Collection of additional parameters

Draft Data - Do not cite or quote 1. Collection of additional habitats Small fish sampling has focused on Bay margins (foreshore) Small fish sampling has focused on Bay margins (foreshore) Limited sampling on wetlands and salt ponds Limited sampling on wetlands and salt ponds –Area of avian wildlife risk –Greater variability in MeHg –May provide clues as to sources Question to Science Advisory Panel: What percent of budget allocation to margins vs. wetlands and salt ponds? Question to Science Advisory Panel: What percent of budget allocation to margins vs. wetlands and salt ponds?

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2. Design – probabilistic vs. gradients and factors Gradient and factor design Gradient and factor design –Select specific attributes expected to be important for Hg exposure –Allows for explicit hypothesis testing

Draft Data - Do not cite or quote Probabilistic design Probabilistic design –Following EPA Generalized Random Tessellation Stratified (GRTS) or some other Spatially- Balanced Survey Design –Bay margin samples chosen along a line tracking bay shoreline –Ensure selection of representative conditions –Determine gradient of relevant parameters for selected sites

Draft Data - Do not cite or quote Question to Advisory Panel Question to Advisory Panel –Which design (factor vs. probabilistic) more appropriate for this project?

Draft Data - Do not cite or quote 3. Collection of additional parameters Aimed at better understanding mechanisms for spatial variation in bioavailable Hg Aimed at better understanding mechanisms for spatial variation in bioavailable Hg Trade off is reduced number of stations Trade off is reduced number of stations Potential parameters: Potential parameters: –Sediment parameters: redox, TOC, grain size, MeHg –Water parameters: TSS, nutrients, chlorophyll –Bathymetry and hydrology: more detailed bathymetric profile and water retention time data –MeHg via Diffusive Gradient Thinfilm devices Recommendation for Advisory Panel to consider – collect ancillary parameters for subset of stations Recommendation for Advisory Panel to consider – collect ancillary parameters for subset of stations

Draft Data - Do not cite or quote Questions – shifts in emphasis 1. Including other contaminants in small fish surveys 2. Studies of food web contaminant uptake

Draft Data - Do not cite or quote Inclusion of other contaminants in small fish surveys Current workplan focuses on MeHg Current workplan focuses on MeHg –Top management priority –Uncertainty of food-web uptake hotspots –Not well characterized by other RMP analyses –Cost leverage (analytical costs ~10x less) Recommendation for Advisory Panel to consider – not include other contaminants in surveys Recommendation for Advisory Panel to consider – not include other contaminants in surveys

Draft Data - Do not cite or quote Studies on mechanisms of contaminant uptake into food web Topics that could be evaluated: Topics that could be evaluated: –Food-web structure –Relative role of sediments vs. the water column as transport pathways of contaminants to biota –Spatial areas that biosentinel species integrate –Spatial variation in food-webs diet Contaminant uptake Currently, not in work plan or anywhere in RMP

Draft Data - Do not cite or quote Source: Bridges et al. 2006

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Available Approaches Review literature and local data from other agencies Review literature and local data from other agencies Dietary analysis of predators (current studies) Dietary analysis of predators (current studies) Stable isotope analysis Stable isotope analysis Food web and contaminant modeling Food web and contaminant modeling –Linkage to contaminant fate and transport models –Models of spatial movement of contaminants in fishes and other biota

Draft Data - Do not cite or quote Examples of results: 1. PCBs in shiner perch as a function of spatial variation in diet Source: Gobas, F. A. P. C., and J. Wilcockson San Francisco PCB food-web model. RMP Technical Report SFEI Contribution #90

Draft Data - Do not cite or quote Source: Greenfield, B. K., A. R. Melwani, J. J. Oram, and S. M. Bay Indicator development and framework for assessing indirect effects of sediment contaminants. SFEI Contribution #524 Examples of results: 2. Water vs. sediment contribution of PCBs

Draft Data - Do not cite or quote Source: Greenfield, B. K., J. A. Davis, C. Roberts, R. Fairey, M. A. Sigala, and J. Negrey The relationship between trophic position, spatial location, and contaminant concentration for San Francisco Bay sport fish: a stable isotope study. Unpublished manuscript Examples of results: 3. Stable isotope (trophic position) vs. Hg in sport fish

Draft Data - Do not cite or quote Question to Advisory Panel Should we incorporate studies on mechanisms of food web contaminant uptake? Should we incorporate studies on mechanisms of food web contaminant uptake? –Currently no effort –Could allocate 10 – 20% of effort to process studies (isotopes/diet analyses) and modeling

Draft Data - Do not cite or quote Summary of questions to Work Group and Advisory Panel (spatial and temporal patterns in food web accumulation) What percent of budget allocation to margins vs. wetlands and salt ponds? What percent of budget allocation to margins vs. wetlands and salt ponds? Which design (factor vs. probabilistic) more appropriate for this project? Which design (factor vs. probabilistic) more appropriate for this project? Do you agree with recommendation to collect ancillary parameters on subset of stations? Do you agree with recommendation to collect ancillary parameters on subset of stations? Do you agree with recommendation not to include other contaminants in small fish sampling? Do you agree with recommendation not to include other contaminants in small fish sampling? Should some effort (e.g., 10-20% of budget) be allocated towards studying processes of food web uptake? Should some effort (e.g., 10-20% of budget) be allocated towards studying processes of food web uptake?