M9 PM Multiple Stressors in Amphibian and Reptile Ecotoxicology
Monday, 14 November 2005: 1:50 PM - 5:30 PM in 339-340

(GRO-1117-837804) Interaction of cadmium and Ribeiroia ondatrae on development and limb malformations in northern leopard frogs.

Gross, J¹, Johnson, P¹, Prahl, L¹, Schowalter-Hay, E¹, Chen, T¹, Karasov, W¹, ¹ University of Wisconsin - Madison, Madison, Wisconsin, US

ABSTRACT- Concerns over global amphibian population declines have prompted research on the interactions of multiple stressors in amphibian development. Pollutants such as cadmium have been shown to alter immune function in vertebrates which may contribute to an increased risk to pathogens. This study examines the effects of cadmium on an amphibian trematode pathogen, Ribeiroia ondatrae, and its interaction with cadmium on northern leopard frog development. Initially the effects of cadmium on survival and development in miracidia and survival and swimming activity in cercariae (both free swimming stages) were assessed. R. ondatrae cercariae were shed from wild-caught snail (Planorbella trivolvis) hosts and adult trematodes were excised from two week old single comb white leghorn chickens Gallus domesticus for ova collection. Leopard frog embryos and tadpoles (n=300) were exposed (control, 1.0, 10.0 g/l, as CdCl2; static renewal system) to sublethal doses of cadmium from embryonic stages to complete tail resorption. Tadpoles (n=109) were individually exposed to R. ondatrae cercariae (n=91) at limb bud stages of development (Gosner stages (GS) 26-29), and tadpole survival, growth (snout vent length), development (GS), and time to metamorphosis was recorded. Tadpole survival was >95% through two weeks of development (prior to parasite infections) for all treatments. Tadpoles exposed to 10.0 g/l Cd demonstrated more rapid growth and development by two weeks (P<0.001 and P<0.01 respectively) relative to all treatments. Parasite infestation, cyst survival, and limb malformations were also recorded in tadpoles. This is the first study examining the effects of cadmium on R. ondatrae′s free swimming life stages and the first study of the interactive effects of the trematode and a heavy metal on parasite infestation, and survival, development, and hind limb malformations in an amphibian. [Supported by Sea Grant R/MW-84, EPASTAR Predoctoral Fellowship]

Key words: amphibian, heavy metals, malformations, parasite