Jollyville Plateau Salamander (Eurycea tonkawae)
The Eurycea tonkawae, more commonly known as the Jollyville Plateau Salamander, is one of four species of interest considered threatened in the Brazos River basin. The existence of this completely aquatic salamander helps identify water quality of particular areas.
The Jollyville Plateau Salamander is listed as Federally Threatened by the U.S. Fish and Wildlife Service (due to a limited geographical range and degradation of its habitat. Threats to this species include urbanization, pollution, and changes in spring flow due to natural causes or man-made pollution.
The Jollyville Plateau Salamander is found only in springs within Brushy Creek, Bull Creek, Cypress Creek, Long Hollow Creek, and Walnut Creek in Travis and Williamson counties.
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The Jollyville Plateau Salamander is one of many spring-associated salamanders found on the Edwards Aquifer system. The San Marcos and Barton Springs Salamanders receive much attention due to their closeness to major human recreation areas and the small size of the area they inhabit. These salamanders are indicator species for changes in water quality and decline in their habitat due to environmental changes and pollution generated by humans.
Photo courtesy of Nathan Bendik
The Jollyville Plateau Salamander lives only in water under rocks and in gravel. This species only occupies spring outflows, which are characterized by clear water, stable temperatures, and stable water chemistry. Water characteristics change greatly with distance from the spring outflow, and salamander populations diminish quickly with minimal distance from the springs.
Little is known about the reproduction of the Jollyville Plateau Salamander. However, this species likely deposits eggs in gravel substrates in the same habitat with adults. These salamanders are paedomorphic, meaning they retain some juvenile characteristics as adults. The larvae hatch with external gills that are retained into the adult form. The adult salamanders likely feed on aquatic invertebrates such as seed shrimp, copepods, and amphipods, according to the U.S. Fish and Wildlife Service and Texas Parks and Wildlife Department.
Researchers determined the Jollyville Plateau Salamander reproduces seasonally in fall and winter and found numerous individuals that were pregnant multiple times during a season, meaning they can reproduce multiple times per year (Bendik et al. 2017).
Ongoing Research/Conservation Efforts
The Jollyville Plateau Salamander’s status as threatened is up for review in 2020 by the U.S. Fish and Wildlife Service, where determinations will be made to either remove the species from the list or change the status from threatened to endangered. Researchers at Texas State University examined stress hormones in this species and found that stress was greater in urban areas than in rural ones (Walls and Gabor 2019).
For more information, go to:
- Bendik, N. F. 2017. Demographics, reproduction, growth, and abundance of Jollyville Plateau salamanders (Eurycea tonkawae). Ecology and evolution, 7(13), 5002-5015.
- Diaz, P.H. and J. BronsonWarren. 2018. Salado Salamander Monitoring Final Report 2018. United States Fish and Wildlife Service and Texas Parks and Wildlife Department. Retrieved at https://www.researchgate.net/publication/331429960_Salado_Salamander_Monitoring_Final_Report_2018
- Walls, S. C., & C.R. Gabor. 2019. Integrating Behavior and Physiology Into Strategies for Amphibian Conservation. Frontiers in Ecology and Evolution, 7(234).
Read more about the other threatened species of interest here.