Decline of some west-central Florida anuran populations in response to habitat degradation

Abstract

Recent reports have suggested that a global decline in amphibian populations has taken place during the past few decades. Urban development is thought to affect the richness and abundances of species and, therefore, could be an important cause of decline. We estimated the richness and abundances of anurans in wetlands at a residential development and in similar wetlands at a nearby undeveloped park. The residential development originally was pine flatwoods habitat, as is the undeveloped park currently. We also compared the anuran species' composition of the park in 1992 with the composition in 1974.Both richness and abundances of anurans in the residential development were different than those in the undeveloped park. Employing the same amount of sampling effort at both sites, we trapped or observed 11 species at the development and 15 species at the park, and trapped 569 individuals at the development and 1224 individuals at the park. The anuran species richness at the undeveloped park in 1992 was nearly the same as in 1974; a single rare species apparently was not present in 1992. Of the 15 species present in both surveys, 14 showed higher abundances in 1992 than in 1974.We suggest that the current differences between the residential development and the park have resulted from degradation of both the uplands used by many species during the dry season and the temporary wetlands used by many species for reproduction. Four species especially sensitive to such degradation, Bufo quercicus, Scaphiopus h. holbrookii, Hyla femoralis, and H. gratiosa, were the species missing from the residential development.Not all species of anurans typical of pine flatwoods appeared to be affected adversely by development. Three species of ranids, Rana utricularia, R. grylio, and R. catesbeiana, were found in higher abundances at the residential development than at the park. These ranid species breed in a wide variety of aquatic systems, including the permanent bodies of water that are now abundant in the development, and probably use the uplands less than other anurans. If amphibian decline is international in scope, then the decline could be attributable either to global changes caused by humans, or to local, but widespread, environmental degradation, or to a combination of factors. While much recent popular focus has been on potential global causes of decline, we believe that this emphasis may have caused attention to be taken away from local causes that, as our study demonstrated, may be at least as important. We suggest that in many places, local environmental degradation is insidiously chipping away at amphibian diversity, and that more emphasis should be placed on these local causes than is now the case.

Pesticide concentrations in frog tissue and wetland habitats in a landscape dominated by agriculture

“…For example, in Eastern Europe amphibians breed successfully in man-made drainage ditches (Hartel et al, 2001), in the Midwest, certain species persist despite agrochemical inputs and habitat modifications (Kolozsvary and Swinhart, 1999;Gilliland et al, 2001) and in Florida not all species of anurans appeared to be adversely affected by development as long as permanent habitat was available for breeding (Delis et al, 1996). In areas of California where habitats have been altered by human activities many of the amphibian species (with the exception of Ambystoma californiense) have significantly declined (Davidson et al, 2002).…”

The cause of global amphibian declines: a developmental endocrinologist's perspective

“…Habitat modification (loss) has played a significant role in many declines and is likely the single most important cause of local declines (Adams, 1999;Becker et al, 2007;Davidson et al, 2002;Davidson et al, 2001;Delis et al, 1996;Eigenbrod et al, 2008;Harper et al, 2008;Smith et al, 2009). Other factors may explain many local declines including the use of road salt, catastrophic events, etc.…”

Ichthyophonus-like infection in wild amphibians from Québec, Canada

“…Numerous causes have been proposed to account for these declines, including habitat loss (Delis et al 1996), climatic changes (Pounds et al 1999), use of pesticides and other agricultural chemicals (Bishop et al 1999), increased UV-B irradiance (Blaustein et al 1998), introduced species (Fisher & Shaffer 1996), and disease (Berger et al 1998).…”