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 Mercury in San Francisco Bay-Delta Birds: Trophic Pathways, Bioaccumulation, and Ecotoxicological Risk to Avian Reproduction San Francisco Bay Estuary HEMISPHERIC IMPORTANCE FOR WATERBIRDS 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 Forsters Tern Nest MeHg Reduces Reproductive Success Bird Mercury Questions 1.Mercury differences among species. 2.Spatial and temporal trends in bird and egg mercury. 3.Relate mercury concentrations to reproductive risk. 4.Fish as wildlife indicators? 5.Implications for TMDL implementation. Littoral Foragers insects & crustaceans American avocet Black-necked stilt Obligate Piscivores - fish Forsters tern Caspian tern Species Studied 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 Radiomarked & tracked Birds Captured Released Mercury Analyzed at USGS Davis Field Station Mercury Lab Methods Whole blood drawn Prey fish collected Telemetry based Methods Continued Nesting monitored Birds Captured SpeciesPre-breedingBreedingTotal Avocet Stilt Forsters tern Caspian tern Total Captures = 668 Bird Mercury Concentrations 3. Mercury concentrations increased over time P < Mercury differed among species 2. Mercury concentrations differed among regions Forsters tern Blood Hg (ppm ww) Date 4/1 4/10 4/20 4/30 5/10 5/20 5/30 North BayCentral BaySouth Bay Forsters Tern Male Hg > Female Hg (P = 0.003) Breeding > Pre-breeding (P < ) Blood [Hg] (ppm ww) North Bay > Central Bay < South Bay (P = 0.03) Male Female Pre-breed Breed What Does this Mean for Birds? Risk Factor Analysis Based on Evers et al (common loon) & Heinz and Hoffman 2003 (mallard) Documented Effects at Population Level >4Extra High Documented Effects: Molecular, Cellular, Behavioral, Potential Population Effects 34High Potential Effects; Reduced Egg Hatchability 13Moderate Undocumented; Minimal Effects