AMPHIBIAN REPRODUCTIVE SUCCESS IN WETLANDS

Abstract

Aerial photograph of the Pinkston mitigation site, Missouri Department of Transportation, showing the presence of six of our experimental mitigation wetlands. Inset are three species of frogs that were encountered during the course of our study (top, leopard frog; middle, gray tree frog; bottom; chorus frog). Photographs by R. Semlitsch. We examined the influences of within-wetland slope, vegetation, and stocked mosquitofish (Gambusia affinis) on amphibian metamorph production and species richness during the first two years post-construction at 18 experimental wetlands in northeast Missouri grasslands. We measured total amphibian metamorph production, individual amphibian species metamorph production, and larval amphibian species richness. Total amphibian metamorph production was greatest at shallow-sloped, fishfree wetlands during the first year, but shallow-sloped wetlands with high vegetation cover were best the second year. Species richness was negatively associated with fish and positively associated with vegetation in both survey years. Leopard frog (Rana blairi/sphenocephala complex) metamorph quality, based on average metamorph size, was influenced by slope and the number of cohorts in the wetland. However, the tested variables had little influence on the size of American toads (Bufo americanus) or boreal chorus frogs (Pseudacris maculata). Our results indicate that wetlands designed to act as functional reproductive habitat for amphibians should incorporate shallows, high amounts of planted or naturally established vegetation cover, and should be fish free. These photographs illustrate the article “Testing wetland features to increase amphibian reproductive success and species richness for mitigation and restoration,” by Christopher D. Shulse, Raymond D. Semlitsch, Kathleen M. Trauth, and James E. Gardner, tentatively scheduled for publication in Ecological Applications 22(5), July 2012.