Fish reduce anuran abundance and decrease herpetofaunal species richness in wetlands

Abstract

Summary For aquatic herpetofaunal species, two of the possible determinants of density and local species composition are fish presence or absence and hydroperiod; factors which are sometimes, but not always, correlated. We quantified wetland herpetofaunal assemblages in 20 wetlands that varied in both attributes (in south‐eastern Florida, U.S.A.) to examine the effects of fish, wetland permanence and their potential interaction. Fish presence significantly reduced the density of five anuran species and reduced overall species richness. Wetland permanence had no measured effect on composition or richness of herpetofaunal assemblages. Three anuran species (including the imperilled Gopher Frog, Rana capito) were absent from most of the wetlands with fish and capture rates of two larger generalist ranids (Rana grylio, R. sphenocephala) were significantly lower in the presence of fish. No species of anuran was captured more frequently when fish were present. Non‐permanent wetlands are often perceived to be quality anuran habitat, but such a perception may be incorrect for wetlands that rapidly recolonise with fish. Dredging and ditching of otherwise temporary wetlands, and fish stocking, may lead to local, and potentially regional, reductions in anuran breeding habitats, especially for faunal assemblages that lack anurans that thrive when fish are present.