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Mercury in Biosentinel Fish in San Francisco Bay

Mercury in Biosentinel Fish in San Francisco Bay. Ben Greenfield 1 , Andrew Jahn 2 , Letitia Grenier 1 , Mark Sandheinrich 3 1. San Francisco Estuary Institute, Oakland, CA 2. 1000 Riverside Drive, Ukiah, CA 3. River Studies Center, University of Wisconsin – La Crosse.

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Mercury in Biosentinel Fish in San Francisco Bay

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  1. Mercury in Biosentinel Fish in San Francisco Bay Ben Greenfield1, Andrew Jahn2, Letitia Grenier1, Mark Sandheinrich3 1. San Francisco Estuary Institute, Oakland, CA 2. 1000 Riverside Drive, Ukiah, CA 3. River Studies Center, University of Wisconsin – La Crosse

  2. Key Management Questions • Assessment of ecological risk to fish and wildlife • Spatial and temporal mercury trends in the Estuary • Is risk of mercury exposure spatially variable, and are these risks predictable? • What are trends in bioaccumulation of Hg vs. wetland restoration and TMDL activities • Building upon conceptual models of Hg exposure

  3. Sampling Design • Multiple sites in San Francisco Bay margins • Wetland restorations vs. extant marshes • Benthic and pelagic species • Topsmelt, Mississippi (inland) silversides • Arrow and cheekspot goby • Additional collection in Bay shoals and channels • Bay goby, herring, anchovy (IEP Bay Study)

  4. 5-10 individuals per composite 4 composites per species per site to allow statistical comparison Used size limits to reduce influence of any length:Hg relationships Compositing Design

  5. Primary Sampling Locations Benicia Park China Camp Extant Marsh Point Isabel Restoration Area Oakland Middle Harbor Candlestick Point Eden Landing Bird Island/ Steinberger Slough Newark Slough Alviso Slough

  6. Opportunistic Locations USFWS Survey IEP Bay Study Primary Location

  7. Preliminary Results • Results from 97 samples in 2005 and preliminary results from 114 samples in 2006 • 17 seining locations and 9 trawling locations (IEP) • 10 Species Inland silversides Animal Diversity Web Image by Mami Odaya, SFEI

  8. Patterns among pelagic species Hg wet weight (g/g)

  9. Patterns among pelagic species Effects threshold for fish (Beckvar et al. 2003) Hg wet weight (g/g) TMDL Target for prey fish to protect piscivorous wildlife

  10. Patterns among benthic species Hg wet weight (g/g) TMDL Target

  11. Anchovy Herring Conceptual model • Variation among species • Mississippi Silverside > Topsmelt and wetland gobies > Bay Goby • Spatial patterns • Alviso Slough elevated in cheekspot goby • South Bay elevated in silversides Polyhaline wetlands/margins Euhaline Bay open waters Higher Hg in fish Lower Hg in fish (cl oser to sources/methylation) (hydraulic mixing dilutes MeHg) Topsmelt Silverside Benthic Pelagic Arrow Goby Cheekspot Goby Bay Goby

  12. Why were arrow and cheekspot gobies higher in 2006? Hg wet weight (g/g)

  13. Broader size range in 2006 Arrow goby

  14. Broader size range in 2006 Cheekspot goby

  15. Comparison to fish/wildliferisk thresholds * Tissue concentration dry weight

  16. Spatial Patterns USFWS Survey ‘06 (Topsmelt) Primary

  17. Hg wet weight (g/g) • 2005 cheekspot goby significantly elevated in Alviso Slough Letters indicate results of ANOVA followed by Student-Newman-Keuls test

  18. 2006 arrow goby elevated in southern stations

  19. 2005 silverside significantly elevated in southern stations Hg wet weight (g/g) • 2006 silverside elevated in Point Isabel

  20. 2005 topsmelt elevated in southern stations (not significant) • 2006 elevated in southern stations, Pt. Isabel, and Tiburon

  21. Why are concentrations often elevated in southern stations and Pt. Isabel?

  22. Urban dump with disposal of car batteries and other metal waste Enclosed wetland with long drainage canal Recall conceptual model – wetland methylation Point Isabel Source: Google Earth

  23. Steinberger Slough/Bird Island Pt. Isabel China Camp Benicia State Park Source: Google Earth Source: Google Earth

  24. Southern stations • RMP data indicate higher sediment MeHg in southern stations • High sediment MeHg in Tiburon Source: RMP

  25. Results Summary • Some samples above TMDL risk threshold for wildlife risk • Variation among species • Mississippi silverside > topsmelt, anchovy, herring • Arrow and cheekspot goby > Bay goby • Spatial patterns • Southern locations higher trend • Pt. Isabel – interior wetland

  26. What’s the big picture? • Variable wildlife risk as a function of target prey and habitat • Conceptual model: different exposure in Bay margins vs. open-water areas • Are there more “Point Isabels” throughout the Bay? • What drives spatial variation? • Sources (e.g., historic Hg mining in South Bay watershed) • Net Methyl Hg production in sediments (many drivers may vary: sulfur, reducing bacteria, salinity, water retention time)

  27. Plans for 2007 and beyond • First year project report available • ben@sfei.org • www.sfei.org • Same general sampling design funded through 2008 – begin trends analysis • Organics analyses in 6 composite samples

  28. Thanks to… April Robinson Aroon Melwani John Oram Rick Wilder Steve Slater Carrie Austin Collin Eagles-Smith Darell Slotten Max Delaney Fred Hetzel Meg Sedlak Mami Odaya Arthur Fong SF Bay National Wildlife Refuge USFWS Stockton USGS BRD California State Parks CA Department Fish & Game Interagency Ecological Program Image by Mami Odaya, SFEI

  29. Topsmelt – also no obvious difference between years

  30. Mississippi silverside 2005 • Combine FMP and RMP data • Results indicate highest concentrations in South Bay fish Unpublished data provided by Darell Slotton

  31. External Coordination • This project:Margins of South, Central, and North Bay • Fish Mercury Project: Central Valley, Delta, and North Bay – more freshwater focus • South Bay Salt Pond Hg Project: Marshes, ponds, and sloughs • CBDA Bird Hg Project: Avian forage fish • Petaluma Hg Project: Marsh fish in Petaluma • Produce comparable data sets by sampling same species

  32. Fish vs. Sediments South Bay San Pablo Bay Hg wet weight (g/g) Silversides 2005 Sediment

  33. Small Fish Hg Project 3

  34. Hg wet weight (g/g) Topsmelt 2005 Mississippi Silverside 2005

  35. Bay goby • Spatial pattern confounded by fish size • Try to limit size range

  36. Cheekspot goby

  37. Striped bass Hg concentrations in SF Estuary over time For more information on sport fish monitoring, see poster # 27

  38. Small Fish Hg Project • Background • Mercury (Hg) in N. California waters a longstanding management concern due to historic mining • Elevated concentrations in sport fish • San Francisco Estuary site of extensive wetland restoration activity • Sensitive wildlife in region

  39. Why Small Fish? • Most sport fish over health advisory threshold (0.3 ppm) • TMDL has small fish targets but there are limited data from Bay • Contaminant pathway to sport fish poorly known • Effect of extensive wetland restoration Hg, ppm wet wt. 2.0 0.2 Jacksmelt Ca. halibut Shiner perch Wt. sturgeon Wt. croaker Striped bass Leopard shark

  40. Regional Monitoring Program Small Fish Project Goals • Monitor food-web mercury at fine spatial and temporal scales • Assess regional trends in bioaccumulation of Hg related to wetland restoration • Develop conceptual model of Hg availability to prey fishes • Collect prey fish appropriate for wildlife risk evaluations

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