Written by Bryan Watts
June 4, 2008

The increasing availability of environmental mercury in aquatic ecosystems across North America and the associated human health implications have resulted in the establishment of fish consumption advisories across large geographic areas. The impact of current mercury levels on wildlife populations is poorly understood but the focus of an expanding community of researchers. Species such as bald eagles, that are positioned near the top of the aquatic food web are believed to be particularly vulnerable to increased mercury concentrations and may represent good biological indicators. However, no recent studies have investigated mercury levels in the Chesapeake Bay eagle population.

Decending from a 200-foot high eagle nest. Photo by the Center for Conservation Biology.

In the spring of 2008, CCB in partnership with the U.S. Department of Defense, initiated an investigation of mercury levels in bald eagles within the Naval Support Facility at Indian Head on the Potomac River. CCB hopes to expand the sampling base to other locations throughout the Chesapeake to establish baseline mercury levels for future comparisons.

Bryan Watts climbs into bald eagle nest to retrieve chicks. Photo by the Center for Conservation Biology.

CCB biologists are collecting blood and feather samples from eaglets to evaluate mercury loads. Because nestlings are fed prey from the surrounding waters, they represent good local indicators of local mercury conditions. Sampling is scheduled to continue through the 2009 breeding season.

Libby Mojica with Indian Head biologist, Seth Berry, banding an eaglet. Photo by the Center for Conservation Biology.