Evaluation, Assessment, and Determination of Risk to High Trophic Level Piscivores in the Mid-Atlantic: A Spatial, Biological, and Comparative Case Study of Mercury in Virginia and New England Bald Eagle (Haliaeetus Leucocephalus) PopulationsEPA Grant Number: F6C20816
Title: Evaluation, Assessment, and Determination of Risk to High Trophic Level Piscivores in the Mid-Atlantic: A Spatial, Biological, and Comparative Case Study of Mercury in Virginia and New England Bald Eagle (Haliaeetus Leucocephalus) Populations
Investigators: Kramar, David Eldridge
Institution: Virginia Polytechnic Institute and State University
EPA Project Officer: Michaud, Jayne
Project Period: September 1, 2006 through August 31, 2009
Project Amount: $111,172
RFA: STAR Graduate Fellowships (2006) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Geospatial and Environmental Analysis , Mercury
This research will focus on determining the current levels of mercury (Hg) in Virginia’s juvenile bald eagle population and identifying the factors that are driving those levels. Samples will be collected from distinct regions within the state, analyzed, and the results mapped in an effort to determine “at risk” areas. Mercury levels in Virginia eagles will be compared to those in Maine’s bald eagle population in an effort to address the sources of variation in two distinct regions of the eastern US.
Blood samples will be collected from the brachial vein in the wing using 21–25 gauge butterfly needles (depending on the size of the juvenile) and 5cc vaccutainers. Analysis of blood mercury in samples will follow analytical methods approved by the U.S. Environmental Protection Agency (EPA). Full metrics will be collected, including but not limited to weight, crop size, foot pad, and halix claw size. In addition to the morpho-metrics of the juvenile eagles, full metrics of the nest tree will be collected if that information is not currently available. Resulting mercury levels will be correlated with predominant land-cover type, foraging area (e.g., lake, river, estuarine), aspect, predominant prey type, and geographic location, and other variables still to be determined. A combination of linear and non-linear modeling techniques such as Poisson log-linear regression, geographic weighted regression, and standard linear regression, implemented in a Geographic Information System, will be used to produce a best fit model of mercury risk in the region. To compare levels between Virginia and Maine, categorical analysis and the use of odds ratios and relative risk statistics will be used.
I predict that some portion of the Virginia bald eagle population will exhibit levels at or above those considered detrimental to productivity and reproductive success. The analysis of independent variables and their relationship to elevated blood mercury levels will help to determine driving factors and explain spatial patterns of blood mercury levels. This will allow for a detailed assessment of mercury risk across the state. The cross-comparative analysis between the Virginia and Maine eagle populations will provide risk assessment at a broader scale. I expect that Maine eagle population will exhibit higher percentages of mercury levels at or above the currently known safe levels.