Synopsis: Mercury and polybrominated diphenylethers (PBDEs) are two persistent, bioaccumulative, and toxic chemicals that may impact animal behavior and harm Great Lakes wildlife. The early and sub-clinical effects of these chemicals may be realized by utilizing neurochemical biomarkers, which are a sensitive and emerging class of biomarkers recently used to assess wildlife health in Northeastern States and Provinces and the Arctic . The specific aims of this proposal are: 1) Exposure Assessment : to determine tissue mercury and PBDE levels in river otters and bald eagles from several Great Lakes states, with a focus on animals collected from existing statewide monitoring programs in Michigan and Wisconsin; 2) Health Assessment : to determine river otter and bald eagle health status by means of neurochemical biomarker studies on key receptors (muscarinic, glutamate) and enzymes (monoamine oxidase, cholinesterase) in physiologically important brain regions; 3) Risk Characterization : to determine if there is a statistical association between mercury and PBDE exposure (Aim #1) and alterations in neurochemical biomarkers (Aim #2); and 4) Education and Capacity Building : to build capacity among academic researchers and government/state managers and to disseminate results to scientific and regulatory communities. The outcome of this work will be integrated into two existing statewide ecosystem monitoring efforts, and will provide managers and regulators with sensitive new information concerning potentially early and sub-clinical health effects in key wildlife sentinels that can be used to better to inform policy decisions.

Chemicals Studied: The project is studying mercury, selenium, and PBDE levels (PBDEs).

Geographic Areas: This project will focus on animals collected from existing statewide monitoring programs in Michigan and Wisconsin.

Methods Used: Tissues (i.e., whole brain, liver, muscle, fur/feather) from 120 individuals of each species. Collection of tissues will be coordinated by collaborators (managers and scientists in state and federal agencies) that oversee and/or are involved with monitoring
programs in Wisconsin and Michigan. All tissues will be analyzed for
mercury (total, organic) and selenium (which should always accompany mercury measurements in wildlife) in PI-Basu’s laboratory at the University of Michigan using established methods. Concentrations of PBDE will be determined using two approaches. First, concentrations will be assessed in brain (cortex section) and liver tissues using a commercially
available enzyme linked immunosorbent assay (ELISA) that uses paramagnetic particles attached with antibodies specific to PBDE (mainly BDE-47 and BDE-99). Following a brief reaction period, PBDE concentrations will be determined spectrophotometrically. Neurochemical biomarkers will be measured in cellular membranes (for binding to muscarinic and glutamate receptors) and cytosolic fractions (for enzyme activities of cholinesterase and monoamine oxidase) isolated from the tissue sections using standard methods in homogenization and differential centrifugation.

Potential Results and Implications: The key outcomes of this project will include: A) a database/spreadsheet of tissue mercury, selenium, and PBDE levels in river otters and bald eagles from several Great Lakes
states (geographic trends, inter-tissue comparisons); B) improved understanding of whether mercury and PBDEs, at current exposure levels, may be causing sub-clinical alterations to the health of two key wildlife sentinels (regression modeling, comparison to available thresholds);
and C) increased capacity among academic researchers (PI-Basu and his laboratory; collaborators Wierda and Bowerman at Clemson) and government/state managers (focus on Michigan and Wisconsin; Collaborators Strom, Cooley, and Route) to synergistically tackle
common issues.

Project Contact:
Niladri Basu
Assistant Professor
Dept. of Environmental Health Sciences
University of Michigan, Ann Arbor
Phone: (734) 764-9490
Email: niladri@umich.edu