Adverse effects of environmentally relevant dietary mercury exposure in larvae of the southern leopard frog, Rana sphenocephala
JASON UNRINE, CHARLES JAGOE, WILLIAM HOPKINS AND HEATHER BRANT
Savannah River Ecology Laboratory, University of Georgia, P.O. Drawer
E. Aiken, South Carolina 29803, USA
Abstract: We exposed larvae of the southern leopard frog
(Rana sphenocephala ) to diets supplemented with aufwuchs
(periphyton and associate organisms) from control and mercury (Hg) enriched
mesocosms combined in proportions intended to mimic mercury concentrations
and speciation in aujwuchs observed from aquatic systems contaminated
by atmospheric deposition. Actual total mercury (THg) concentrations in
the diets were 54,423, 1409, and 3298 ng Hg/g DW 22 %, 3.4 %, 1.9 % and
1.5 % present as methylmercury (MMHg) for control, low, medium and high
treatments, respectively. Rates of mortality, malformation, larval growth
and development were observed over the entire larval period (60-254 d).
Increased incidence of mortality, malformation, and changes in growth
and development were observed at concentrations that reflect the highest
concentrations expected in the amphibian diet from atmospheric deposition.
The results of this study are probably more ecologically realistic than
results obtained from previous studies of aqueous Hg toxicity and suggest
that dietary Hg exposure in habitats primarily contaminated by atmospheric
deposition has the potential to cause adverse effects in amphibian larvae.
This is the first study to demonstrate the potential for adverse effects
due environmentally realistic Hg exposure in amphibians.
Key words: Amphibian, Diet, Growth, Development, Malformation
SREL Reprint #2777
Unrine, J. M., C. H. Jagoe, W. A. Hopkins and H. A. Brant. 2004. Adverse effects of environmentally relevant dietary mercury exposure in larvae of the southern leopard frog, Rana sphenocephala. Paper 84. In 7th International Conference on Mercury as a Global Pollutant, edited by Milena Horvat, Nives Ogrinc, and Jože Kotnik. Jožef Stefan Institute, Ljubljana, Slovenia.
