John Isanhart

Mercury and selenium contamination in waterbird eggs and their risk to avian reproduction in Great Salt Lake

 
Authors: Josh Ackerman1, Mark Herzog1, Garth Herring1, Alex Hartman1,
Collin Eagles-Smith2, John Isanhart3, Sharon Vaughn4,
John Cavitt5, Josh Vest6
 

1 U.S. Geological Survey, Western Ecological Research Center, University of California, Davis, CA
2 U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, OR
3 U.S. Fish and Wildlife Service, Utah Field Office, West Valley City, UT
4 U.S. Fish and Wildlife Service, Bear River Migratory Bird Refuge, Brigham City, UT
5 Weber State University, Ogden, UT
6 U.S. Fish and Wildlife Service, Intermountain West Joint Venture, Missoula, MT

Mercury contamination is an issue of national conservation concern, especially in wetlands where biogeochemical conditions are known to stimulate microbial methylmercury production. Wetlands provide critical foraging and nesting habitat for migratory waterbirds, which can place them at high risk to deleterious toxicological effects, such as reduced egg hatchability, from methylmercury exposure. Although the GSL’s wetland and saline habitats, and particularly the Bear River Migratory Bird National Wildlife Refuge, host large proportions of continental populations of migratory birds, little is known about the extent to which anthropogenic derived contaminants affect these species.

To address this uncertainty, USGS and USFWS have been collaborating on a 3-year study to identify the areas of greatest mercury and selenium risk to more than 30 species of waterbirds within the wetlands within the Refuge complex and GSL , and study the effects of mercury exposure on egg hatching success. Data acquired from the 2010 breeding season demonstrate that some waterbird species are accumulating elevated levels of mercury in their eggs, including Caspian terns, Forster’s terns, snowy plovers, black-necked stilts, and double-crested cormorants.

Additional on-going studies are necessary to identify the consequences of mercury exposure in waterbirds breeding at the Refuge and other GSL wetlands. Data from this study will provide Refuge staff with site-specific information about wetland management, and which wetland areas are exposing birds to the highest levels of mercury and selenium bioaccumulation. The results from this study, anticipated in 2013, can also be used to inform Great Salt Lake-wide mercury risk assessments that are being led by state and federal agencies. This investigation, which assesses contaminant levels in hundreds of eggs representing more than 30 species of waterbirds, is the most comprehensive assessment of mercury exposure to breeding migratory birds using the Great Salt Lake ecosystem.

Key Words: Bear River Migratory Bird Refuge, Great Salt Lake, mercury, water birds, reproduction, eggs