Wetland characteristics associated with trematode infections in amphibians: Implications for conservation and restoration

Infection by larval trematodes has been implicated in causing limb deformities, behavioral changes, and mortality in amphibians.  The consequences of such effects are likely to impair the sustainability of amphibian populations.  Therefore, effective amphibian conservation and restoration plans, should include strategies to alleviate the intensities of larval trematode infections.  Unfortunately, little is known about the wetland characteristics that promote larval trematode transmission.  To address this lack of knowledge, we applied multivariate techniques to evaluate the characteristics of wetlands that were positively associated with larval trematode infections in amphibian populations of the Midwestern US.  Exposure to contaminants (particularly atrazine), snail species richness, and composition of wetland vegetation were identified as important determinants of larval trematode abundances in recently metamorphosed frogs.  Landscape context of wetlands also strongly influenced abundances, suggesting disease management plans will have to consider the surrounding terrestrial habitats.  Time of year, climatic conditions, amphibian stage structure, and invertebrate and vertebrate communities at wetlands may also be important.  Collectively, our results indicate the need for experimental research to identify the wetland characteristics that may be manipulated to reduce larval trematode infections in amphibians.