Amphibians' life stages influence contaminant transfer from aquatic to terrestrial environments

Scientists at the University of Georgia's Savannah River Ecology Laboratory have taken the first step toward understanding how variations in the life stages of amphibians may influence contaminant transfer from aquatic to terrestrial environments. Using bullfrog larvae from a coal combustion waste-settling basin, the scientists investigated the effects of both developmental stage and the timing of metamorphosis on the concentrations of a series of trace elements in bullfrog tissues. Four stages in all were examined as were both spring and fall metamorphs. The work has just been published in Environmental Toxicology and Chemistry.

"Elimination or retention of trace elements through metamorphosis not only has important implications for the health of recent metamorphs, but also determines the quantities of contaminants leaving the aquatic environment and entering the terrestrial food webs," said William Hopkins, one of the researchers.

Juvenile and adult amphibians are often abundant in aquatic and terrestrial systems and are important prey items in the diets of birds and reptiles, according to Hopkins. He said body burdens of some contaminants, such as selenium and strontium, are retained through metamorphosis and they may be transferred into terrestrial food webs from wetland systems where they are thought to be sequestered. He said more study on the topic is needed. He is planning laboratory experiments that control exposure conditions and duration as a next step.

Joel W. Snodgrass of Towson University and John Roe of Rutgers University are Hopkin's co-authors. SREL is located on the U.S. Department of Energy's (DOE) Savannah River Site (SRS) and the research was funded by a grant from DOE-Office of Biological and Environmental Research, Environmental Remediation Sciences Division (ERSD) to identify, understand and anticipate the long-term health and environmental consequences of energy production, development, and use. The SRS is a former nuclear production facility and a federally designated National Environmental Research Park located near Aiken, S.C.

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