PT12 Metals and Bioaccumulation
Exhibit Hall
8:00 AM - Tuesday
(PT153) Performance of amphibians reared as metamorphs in terrestrial enclosures after chronic larval exposure to cadmium.
James, S1, Semlitsch, R1, Little, E2, 1 University of Missouri-Columbia, Columbia, Missouri, USA2 USGS Columbia Environmental Research Center, Columbia, Missouri, USA
ABSTRACT- Amphibians that survive larval exposure to bioaccumulating contaminants possess a body burden as metamorphs emerging into the terrestrial environment. Ecotoxicological studies of the effects of specific contaminants on amphibians should therefore assess multiple lifestages, both during and after exposure. We reared American toad (Bufo americanus) and southern leopard frog (Rana sphenocephala) larvae separately in outdoor mesocosms (1325-L polyethylene cattle tanks) that had been dosed with 0, 5, 18, 60, or 200 
g Cd/L and raised them through metamorphosis. Survivors were then stocked in 2m2 terrestrial enclosures at a density of 3.5/m2 and the two species were once again kept apart. American toads from all five concentrations were stocked, but high larval mortality of the southern leopard frogs at 60 and 200 g Cd/L prevented stocking at these concentrations. Survival and growth were monitored in the fall after metamorphosis and the following spring. There was a significant effect of Cd treatment on American toad survival, mass, and growth rate in the fall but not the spring. In the fall, American toad survival was only 3% in the two highest concentrations and mean mass and growth rate were greatest in the 18 g Cd/L treatment. No significant Cd effects were found in the southern leopard frogs, but interestingly, the trend of initial mass to increase with increasing Cd was maintained only to the fall. By the spring, the growth and survival of both species were not affected by larval exposure to Cd. This study demonstrates the importance of using more than one species and observing multiple lifestages when determining contaminant toxicity.
Key words: cadmium, amphibian, terrestrial, enclosures