Ecology of the Jollyville Plateau Salamander (Eurycea tonkawae: Plethodontidae) with an Assessment of the Potential Effects of Urbanization

Abstract

The Jollyville Plateau salamander, Eurycea tonkawae Chippindale, Price, Wiens, and Hillis, inhabits springs and wet caves of the Jollyville segment of the Edwards Plateau, Texas. The known range of this species is limited to six stream drainages, and most known localities are at risk of impairment from urban development. Our purpose was to gather needed autecological information on E. tonkawae and evaluate factors that may affect the distribution and abundance of the species. We conducted visual salamander surveys at nine stream sites across the Jollyville Plateau between December 1996 and December 1998. The survey sites were classified as undeveloped or developed based on watershed impervious cover estimates. We characterized the habitat for each site, including substrate type, discharge, and water quality. Salamander counts varied seasonally, but generally were higher during spring and summer. Salamander densities across sites were positively correlated with rubble and cobble substrate density as preferred cover, and negatively correlated with the standard deviation of water temperature, as expected for a spring-adapted species. In addition, we found that mean salamander densities at sites occurring in undeveloped watersheds were significantly higher than at developed sites, where specific conductance of the water was higher. The results of this study suggest that while habitat and seasonal factors influence surface salamander densities, E. tonkawae populations may be most vulnerable to effects associated with urbanization.

Computer-Assisted Photo Identification Outperforms Visible Implant Elastomers in an Endangered Salamander, Eurycea tonkawae

“…Given the low initial error rates observed with Wild-ID, we did not test other software platforms nor attempt to further optimize the Wild-ID scoring algorithm. Photo ID applications aimed at species with more challenging natural marking patterns [20] or species with evolving marks [19] may require either optimization of the Wild-ID scoring algorithm [13] or modeling of the error process. Indeed, new methods are already being developed to accommodate photoID errors in capture-recapture modeling [30] including errors involving evolving natural marks [16].…”

“…Eurycea tonkawae is a small (total length typically <75 mm) neotenic salamander endemic to springs, spring-fed headwater streams, and wet caves in northwest Austin, Texas and surrounding areas, with a total range of <110 km 2 [18], [19]. Our study site includes a small, occasionally intermittent spring (Lanier Spring) and adjacent stream bed (Bull Creek) within the City of Austin’s Balcones Canyonland Preserve, Travis County, Texas.…”

Detection of Batrachochytrium dendrobatidis in Endemic Salamander Species from Central Texas

“…Only one site (Stillhouse Hollow, Austin) resulted in more than one positive detection from any locality (three out of six samples). This site is considerably more impacted by urban development than other sites (Bowles et al, 2006;O'Donnell et al, 2006). Spinal deformities and reduced population size have been reported at this site and been attributed to poor water quality (i.e., high nitrate levels) (O'Donnell et al, 2006).…”

Creating Land use Scenarios for City Greenbelts Using A Spatial Multi-Criteria Analysis Shell: Two Case Studies

“…A group of disconnected preserves within a general conservation area potentially subject to encirclement: the Balcones Canyonland Preserves lie within a broad conservation area on the western side of City of Austin, Texas. The Preserves, mandated in 1996, are designed to protect high-value environmental assets including endangered bird and amphibian species (Engels and Sexton, 1994;Bowles et al, 2006) in the karst savanna-dominated landscape of the Edwards Plateau in Travis County west of the city (Pease and Grzybowski, 1991;Anonymous, 1996).…”