Grants and Contracts Details
Description
Project Summary. Many amphibian declines have been attributed to emergent infectious diseases, but
little is known about how diseases emerge. The goal of this proposed work is to identify factors that
contribute to the emergence of amphibian diseases using amphibians and parasites endemic to Kentucky.
The focal disease organisms are the parasitic digenetic trematodes Ribeiroia ondatrae and Echinostoma
trivo/vis. They are transmitted from snails to amphibians and induce limb deformities and kidney
damage, respectively, that have been associated with extensive amphibian mortality. The underlying
hypothesis is that stressors can interact synergistically to increase trematode transmission and virulence
(parasite-induced lethality). The specific objectives of this project are to determine how trematode
disease properties and amphibian fitness are influenced by 1) the anthropogenic stressors - pesticides and
pond drying (associated with global climate change), and 2) the natural stressors - competition and
predation. To evaluate the effects of anthropogenic stressors (Exp. 1), we will expose mesocosms
consisting of spring-breeding frog tadpoles (Rana pipiens, R sylvatica, Bufo americanus) and R
ondatrae- and E. trivolvis-infected snails to two hydroperiods (dry-down or constant water level) crossed
by eight ecologically-relevant pesticide treatments (water and solvent control, atrazine: 3, 30, 300 /lg/L,
endosulfan: 2, 20, 200 /lg/L). To assess the influence of natural stressors (Exp. 2), two species of
tadpoles, half infected with trematodes and half left un infected, will be reared under two densities in the
presence and absence of caged predators. Half the un infected tadpoles will be exposed to trematode
cercariae at the end of the experiment to assess the influence of treatments on trematode transmission. In
both experiments, parasite transmission, pathogenicity (parasite-induced debilitation) and virulence and
various snail and frog traits (such as growth, behavior, and survival) will be quantified.
Status | Finished |
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Effective start/end date | 5/1/04 → 4/30/05 |
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