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Risk Assessment of Exposure to Lead for Mottled Ducks on National Wildlife Refuge of the Texas Gulf Coast

Brian Kearns, Ph.D Student

Project Supervisors:
Dr. David Haukos
Dr. Warren Conway

U.S. Fish and Wildlife Service
U.S. Geological Survey

Texas Chenier Plain NWR Complex
Stephen F. Austin State University
Dr. Dan Collins
Patrick Walther

Location: Anahuac National Wildlife Refuge

Completion: August 2015

Status: Starting fall 2012.

Mottled ducks are being studied to determine potential impacts of lead exposure on populations of the Texas Gulf Coast

(1) Within the context of a formal risk assessment, evaluate the risk of environmental lead for mottled ducks and other waterbirds.
(2) Model the impacts of lead availability on survival and reproductive of mottled ducks.
(3) Evaluate the effect of lead on the body condition of mottled ducks
(4) Ratio of lead isotopes will be used to determine potential sources of lead in addition to spent lead short.

Progress and Results:
Currently, ongoing studies on the Texas Chenier Plain and Midcoast NWR Complexes are quantifying spatial availability of lead pellets and lead concentrations in the soil, birds, and plants. In addition, that study is also relating environmental lead concentrations with concentrations in blood of mottled ducks and other species. Therefore, the proposed study will combine all of those data and conduct a formal risk assessment of lead for mottled ducks. To determine potential source of lead (i.e., natural or anthropogenic) in these samples, ratios of stable lead isotopes following the methods of Saint-Laurent et al. (2010) will be evaluated. We will use krieging techniques in ArcGIS along with general estimating equations to produce maps for all NWRs that predict probability density functions of lead availability in all sampled habitats across the range of mottled ducks. Using the model being developed for predicting the influence of environmental lead on population demography of mottled ducks on the Texas Chenier Plain NWR, we will estimate the effects of available lead on mottled duck survival and recruitment on the coast of Texas. Recent efforts using population matrix models will be used to assess the effects of lead exposure on reproduction and survival of mottled ducks. Finally, these data will be used to conduct a risk assessment is the determination of the quantitative or value of risk related to a concrete situation and a recognized threat (also called hazard). Risk assessment consists in an objective evaluation of risk in which assumptions and uncertainties are clearly considered and presented. Part of the difficulty of risk management is that measurement of both of the quantities in which risk assessment is concerned - potential loss and probability of occurrence. The collected data will provide these quantities. We will follow the EPA framework for ecological risk assessment, including the following three general phases: (1) problem formulation, (2) analysis, and (3) risk characterization.

Brian Kearns, Stephen McDowell, Jena Moon, Elizabeth Rigby, and David Haukos. 2014. Identifying Landscape-level indicators of environmental contaminants that affect wildlife: a species distribution approach. Graduate Student Research Forum, Division of Biology, Kansas State University.

Brian Kearns presented a paper at the Texas Chapter of The Wildlife Society meeting in Austin, TX. 2014. "The legacy of lead: developing new methods for assessing lead contamination and wildlife exposure risks in Gulf Coast wetland habitats."

Kearns, B.V., McDowell, S., Moon, J., Rigby E., Haukos, D. 2014. Identifying landscape-level indicators of environmental contaminants that affect wildlife: a species distribution approach. Midwest Fish and Wildlife Conference, Kansas City, MO.

Kearns, B., D. Haukos, J. Moon, and E. Rigby. 2013. Species distribution in environmental decision-making: characterizing the efficacy of different models for use in habitat and wildlife management. Annual Meeting of the Society for Conservation GIS. Monterey, California.

Kearns, B., S. McDowell, J. Moon, and D. Haukos. 2013. Spatial analysis and ecological risk assessment for lead exposure in Gulf Coast waterfowl: does environmental lead represent an ecological trap? Annual Meeting of the Ecological Society of America. Minneapolis, Minnesota.