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Mercury Risk to Avian Reproduction in San Francisco Bay: Implications for TMDL Implementation: 

Mercury Risk to Avian Reproduction in San Francisco Bay: Implications for TMDL Implementation Collin Eagles-Smith, Josh Ackerman, Terry Adelsbach, John Takekawa, Keith Miles, Steve Schwarzbach, and Tom Suchanek U. S. Fish and Wildlife Service, Environmental Contaminants Division U. S. Geological Survey, Western Ecological Research Center

Slide2: 

Mercury in San Francisco Bay-Delta Birds: Trophic Pathways, Bioaccumulation, and Ecotoxicological Risk to Avian Reproduction

Slide3: 

San Francisco Bay Estuary HEMISPHERIC IMPORTANCE FOR WATERBIRDS

Slide4: 

Central nervous system effects Altered behavior Impaired vision, hearing, and motor skills Endocrine effects Reduced breeding effort Embryo death Embryo deformities Chick death Wildlife Sensitive to Methyl Mercury Toxicity Forster’s Tern Nest MeHg Reduces Reproductive Success

Bird Mercury Questions: 

Bird Mercury Questions Mercury differences among species. Spatial and temporal trends in bird and egg mercury. Relate mercury concentrations to reproductive risk. Fish as wildlife indicators? Implications for TMDL implementation.

Species Studied: 

Littoral Foragers – insects andamp; crustaceans American avocet Black-necked stilt Obligate Piscivores - fish Forster’s tern Caspian tern Species Studied

Study Sites: 

Study Sites 3 regions North Bay (Napa-Sonoma Marsh) Central Bay (Eden Landing, Newark) South Bay (Don Edwards SFB NWR) North Bay Central Bay South Bay

Slide8: 

Radiomarked andamp; tracked Birds Captured Released Mercury Analyzed at USGS Davis Field Station Mercury Lab Methods Whole blood drawn

Slide9: 

Prey fish collected Telemetry based Methods Continued Nesting monitored

Birds Captured: 

Birds Captured Total Captures = 668

Bird Mercury Concentrations: 

Bird Mercury Concentrations 3. Mercury concentrations increased over time P andlt; 0.0001 P andlt; 0.0001 1. Mercury differed among species 2. Mercury concentrations differed among regions Forster’s tern Blood Hg (ppm ww) 0.1 1 10 Date 4/1 4/10 4/20 4/30 5/10 5/20 5/30

Slide12: 

North Bay Central Bay South Bay Forster’s Tern Male Hg andgt; Female Hg (P = 0.003) Breeding andgt; Pre-breeding (P andlt; 0.0001) 0.1 1 10 Blood [Hg] (ppm ww) North Bay andgt; Central Bay andlt; South Bay (P = 0.03) Male Female Pre-breed Breed

What Does this Mean for Birds?Risk Factor Analysis: 

What Does this Mean for Birds? Risk Factor Analysis Based on Evers et al. 2004 (common loon) andamp; Heinz and Hoffman 2003 (mallard) Documented Effects at Population Level andgt;4 Extra High Documented Effects: Molecular, Cellular, Behavioral, Potential Population Effects 3–4 High Potential Effects; Reduced Egg Hatchability 1–3 Moderate Undocumented; Minimal Effects andlt;1 Low Impact Hg Concentration (ppm) Risk Category Blood (ww) Eggs (dw) 6.8–8 3.2–6.8 andlt;3.2 andgt;8

Slide14: 

North Bay Central Bay South Bay Forster’s Tern 0.1 1 10 Blood [Hg] (ppm ww) Male Female Pre-breed Breed Low Moderate High Extra high Risk Category

Slide15: 

North Bay Central Bay South Bay Stilt 0.1 1 10 Female, breeding Male, pre-breeding Female, pre-breeding Blood [Hg] (ppm ww) Low Moderate High Extra high Risk Category

Slide16: 

Avocet Stilt Forster’s tern Avocet Stilt Forster’s tern Caspian tern Avocet Stilt Forster’s tern Caspian tern Central Bay North Bay South Bay Percent of Population at Risk Site Specific 0% 2% 4% 29% 0% 0% 0% 1% 22% 10% 27% Risk Factor: High + Extra High

Slide17: 

Percent of Population at Risk Breeding Birds Only 6% 5% 10% 58% Risk Factor: High + Extra High

Slide18: 

Avocets Stilts Forster’s Terns Mercury in Eggs Extra High High Risk Category Low Moderate

Slide19: 

Percent of Population at Risk All Eggs 0% 10% 46% Risk Factor: High + Extra High Percent of Population at Risk

Slide20: 

Management andamp; Regulatory Implications Differences in space and habitat use Differences in diet Differences in prey Hg Differences in mercury exposure

Slide21: 

Telemetry Map Stilts 2005 South

Slide22: 

Telemetry Map Avocets 2005 South

Slide23: 

Telemetry Map Forster’s Terns 2005 South

Forster’s Tern Diet by Colony-Estimated from colony returns-: 

Forster’s Tern Diet by Colony -Estimated from colony returns-

Forster’s Tern Diet by Colony-Estimated from colony returns-: 

Forster’s Tern Diet by Colony -Estimated from colony returns-

Prey Fish Hg Concentrations: 

Prey Fish Hg Concentrations Pond A7 Pond A8 Pond A16 North Bay

Fish vs. Egg Mercury Relationships: 

Fish vs. Egg Mercury Relationships

Slide28: 

Fish vs. Egg Mercury Relationships Stickleback Mercury (ppm ww) Colony Egg Mercury ( ppm ww ) 0 1 2 3 0 0.1 0.2 R2 = 0.10 P =0.31 Silverside Mercury ( ppm ww ) Colony Egg Mercury ( ppm ww ) 0 1 2 3 0 0.1 0.2 0.3 Silverside Mercury ( ppm ww ) Colony Egg Mercury ( ppm ww ) 0 1 2 3 0 0.1 0.2 0.3 Mudsucker Mercury ( ppm ww ) Colony Egg Mercury ( ppm ww ) 0 1 2 3 0 0.1 0.2 Mudsucker Mercury ( ppm ww ) Colony Egg Mercury ( ppm ww ) 0 1 2 3 0 0.1 0.2 Goby Mercury Colony Egg Mercury ( ppm ww ) 0 1 2 3 0 0.1 0.2 (ppm ww) R2 = 0.19 P =0.33 R2 = 0.04 P =0.65 R2 = 0.07 P =0.57

Diet-weighted Fish vs. Egg Mercury: Spatially Explicit: 

Diet-weighted Fish vs. Egg Mercury: Spatially Explicit Diet-weighted Fish Mercury (ppm ww) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Colony Egg Mercury (ppm ww) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 + + +

Diet-weighted Fish vs. Egg Mercury: Spatially Explicit: 

Diet-weighted Fish vs. Egg Mercury: Spatially Explicit Diet-weighted Fish Mercury (ppm ww) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Colony Egg Mercury (ppm ww) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 R2 = 0.68 P = 0.01 Need to know bird space use Need to know bird-specific diet Need to know bird prey Hg concentrations

Diet-weighted Fish vs. Egg Mercury: TMDL implications: 

Wildlife target exceeds LOAEL Is wildlife target non-protective? Does LOAEL need refinement? OR Are fish inadequate indicators of avian risk? Diet-weighted Fish vs. Egg Mercury: TMDL implications Diet-weighted Fish Mercury (ppm ww) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Colony Egg Mercury (ppm ww) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 R2 = 0.68 P = 0.01 TMDL Wildlife Target Avian egg LOAEL

Eggs as indicators of wildlife risk: 

Eggs as indicators of wildlife risk Trophic Transfer Maternal Transfer Fail-to-Hatch Hatch Mortality (andlt;10 d) Survive

Eggs as indicators of wildlife risk: 

Eggs as indicators of wildlife risk Trophic Transfer Maternal Transfer Fail-to-Hatch Hatch Mortality (andlt;10 d) Survive

Slide34: 

Birds show high site fidelity Birds are good bioindicators of Hg at small spatial and temporal scales Birds useful for Hg monitoring Conclusions:

Slide35: 

In breeding birds Especially Forster’s terns and potentially other fish-eating birds In eggs Especially Stilts and Forster’s terns Conclusions: Current mercury levels are above toxic thresholds…

Slide36: 

Individual fish species do not adequately represent wildlife exposure. Spatially explicit data on bird habitat use, diet and prey mercury to predict exposure. Eggs are valuable tools for monitoring mercury in Bay-Delta wildlife. Conclusions:

Acknowledgements: 

CALFED Ecosystem Restoration Program: Carol Atkins and Donna Podger Logistical Support: Don Edwards SF Bay NWR (USFWS): Clyde Morris, Joy Albertson, Mendel Stewart, Joelle Buffa, Eric Mruz Eden Landing Ecological Reserve: John Krause Napa/Sonoma Marsh Wildlife Area: Tom Huffman, Larry Wyckoff, Carl Wilcox, Karen Taylor Bird Mercury Project Principles: USGS: Steve Schwarzbach, Tom Suchanek, John Takekawa, A. Keith Miles, Susan De La Cruz US FWS: Tom Maurer, Dan Welsh SFBBO: Cheryl Strong, Janet Hansen PRBO Conservation Science: Nils Warnock, Mark Herzog Field Support: Jill Bluso, Scott Demers, Sarah Stoner-Duncan, Angela Rex, John Henderson, Joe Northrup, Brooke Hill, Kristen Dybala, Eli French, Ross Wilming, Lindsay Dembosz, Cathy Johnson, Lani Stinson, Kevin Aceituno Emily Eppinger, Mychal Truwe, River Gates, Mali Nakhai, Lab Support: Robin Keister, Sarah Spring, Liz Bowen Acknowledgements

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