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Wading birds as bioindicators of mercury contamination in Florida, USA: annual and geographic variation

Environmental Toxicology and Chemistry

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Abstract

Mercury contamination in wetland biota is often dynamic, difficult to predict, and costly to track. In this paper, we present results from a six-year study of growing feathers of piscivorous birds as monitors of wetland Hg exposure in Florida, USA, wetlands. Between 1994 and 2000, we collected feathers of growing great egret (Ardea alba) nestlings from colonies in the freshwater Everglades of southern Florida, and during 1998, feathers were collected from chicks of both great egrets and white ibises (Eudocimus albus) at a variety of colonies throughout peninsular Florida. Coastal colonies showed significantly lower feather Hg concentrations than did inland sites. Within the Everglades, we found significant effects of both geographic location and year on age-adjusted mean total Hg concentrations in feathers. Over the course of our study, Everglades colonies maintained their Hg concentration rankings relative to one another, but all showed strongly declining Hg concentrations (mean of 73% averaged across colonies, between 1994 and 2000). Using a previously established predictive relationship between Hg consumption in food and feather Hg for great egrets, we estimated that Hg concentrations in the aggregate diet of egrets have been reduced by an average of 67%. We conclude that the Everglades has undergone a biologically significant decline in Hg availability in the wetland food web, possibly because of decreased local inputs.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Wading birds as bioindicators of mercury contamination in Florida, USA: annual and geographic variation
Series title:
Environmental Toxicology and Chemistry
Volume
21
Issue:
1
Year Published:
2002
Language:
English
Contributing office(s):
National Wildlife Health Center
Description:
p. 163-167
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Toxicology and Chemistry
First page:
163
Last page:
167
Country:
United States
State:
Florida
Online Only (Y/N):
N
Additional Online Files(Y/N):
N