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