thumbnail

Landscape factors and hydrology influence mercury concentrations in wading birds breeding in the Florida Everglades, USA

Science of the Total Environment

By:
, , , , and
DOI: 10.1016/j.scitotenv.2013.04.036

Links

Abstract

The hydrology of wetland ecosystems is a key driver of both mercury (Hg) methylation and waterbird foraging ecology, and hence may play a fundamental role in waterbird exposure and risk to Hg contamination. However, few studies have investigated hydrological factors that influence waterbird Hg exposure. We examined how several landscape-level hydrological variables influenced Hg concentrations in great egret and white ibis adults and chicks in the Florida Everglades. The great egret is a visual “exploiter” species that tolerates lower prey densities and is less sensitive to hydrological conditions than is the white ibis, which is a tactile “searcher” species that pursues higher prey densities in shallow water. Mercury concentrations in adult great egrets were most influenced by the spatial region that they occupied in the Everglades (higher in the southern region); whereas the number of days a site was dry during the previous dry season was the most important factor influencing Hg concentrations in adult ibis (Hg concentrations increased with the number of days dry). In contrast, Hg concentrations in egret chicks were most influenced by calendar date (increasing with date), whereas Hg concentrations in ibis chicks were most influenced by chick age, region, and water recession rate (Hg concentrations decreased with age, were higher in the southern regions, and increased with positive water recession rates). Our results indicate that both recent (preceding two weeks) hydrological conditions, and those of the prior year, influence Hg concentrations in wading birds. Further, these results suggest that Hg exposure in wading birds is driven by complex relationships between wading bird behavior and life stage, landscape hydrologic patterns, and biogeochemical processes.

Study Area

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Landscape factors and hydrology influence mercury concentrations in wading birds breeding in the Florida Everglades, USA
Series title:
Science of the Total Environment
DOI:
10.1016/j.scitotenv.2013.04.036
Volume
458-460
Year Published:
2013
Language:
English
Publisher:
Elsevier
Contributing office(s):
Forest and Rangeland Ecosystem Science Center
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Science of the Total Environment
First page:
637
Last page:
646
Country:
United States
State:
Florida
Other Geospatial:
Everglades National Park