New Study Suggest Genetic Variation of Fern Bank Salamander Unique to Jacob’s Well Spring

In March of this year, a team of Biologists from Zara Environmental and Texas State University published the results of an exciting recent study of Eurycea pterophila (the Fern Bank Salamander) in The Southwestern Naturalist. The purpose of the study was to determine whether the site, Jacob’s Well, is home to a single recognized species or more than one distinct species adapted to both spring and cave environments and whether this particular population is isolated from other closely related salamanders inhabiting Central Texas springs. The study was based on specimens collected between May 2009 and June 2011 and was more extensive than any previous study at the site in terms of number of dives and distribution of samples collected throughout the cave. Almost all of the salamanders were collected following high spring flow events of 25-70 cubic feet per second (cfs), and virtually none were observed or trapped during flows lower than 10 cfs. The scientists also documented Fern Bank salamanders at greater depths than any previous study, 43 meters below the surface, and collected many very small juveniles more than 42 meters into the cave. They then genetically characterized 69 salamanders, comparing them to other populations in the region, and concluded that they were all the same species, Eurycea pterophila. 

The study yielded several valuable findings, raised key questions for further study and underscored the unique ecological and scientific value of Jacob’s Well. Although the same species occurs at other sites in Central Texas, Jacob’s Well contains genetic variations important to the species as a whole. Further study is needed to determine whether or not this population is indeed currently isolated from others. However, “the results indicate that the population from Jacob’s Well has either current or historical contact with one of the parental populations” present in other springs.1 More conclusively, the greater number of samples following high spring flow and the presence of juvenile salamanders so deep within the cave strongly suggests that reproduction occurs deeper within in the cave meaning that the “aquifer habitat may serve as breeding grounds or vital refuge during drought.”2 Jacob’s Well is one of the only springs in Central Texas large and therefore accessible enough to study spring-dwelling creatures such as the Fern Bank salamander in its natural habitat. The iconic spring provides not only the habitat to a unique variation of the species but also a rare natural laboratory for future research. In addition to strengthening scientific understanding of these elusive creatures, this important study reinforces the need to enact management strategies for minimum spring flow protections and keep these Central Texas treasures clean, clear, and flowing.