Abstract

Amphibians are a unique class of organisms with a very long and storied evolutionary history of survival. Many modern amphibian clades occupy several vital ecological roles within their native freshwater environments. One of these roles, typically includes functioning as an ecological indicator species, whereby the presence of stable and diverse populations of many amphibian species, including salamanders, within a freshwater ecosystem have long been considered ecological indicators of good habitat quality and stable ecosystem health. Similarly, salamanders also function as important members of their local food webs and act as valuable mediators of complex trophic hierarchies to facilitate nutrient cycling between trophic levels throughout their equally complex life histories.

However, countless amphibians today are experiencing significant population declines – with many sensitive and endemic species currently facing the imminent threat of widespread extinction events that are primarily driven by anthropogenic activities. Concerningly, this could also spell disaster for numerous other clades and communities within these same freshwater ecosystems. These changes in amphibian distribution and diversity are only one small component in many broad scale declines in global biodiversity that have been recognized in recent decades. These collective declines have been described as a “sixth mass extinction.” Because of their status as ecological indicator species, the widespread reduction in many amphibian communities may also serve as a harbinger of further biological crises in the near future.

As a result, an updated record of sensitive amphibian species, especially salamanders, needs to be collected and compiled for use in assessing, tracking, and maintaining the health and well-being of many vital freshwater ecosystems. Here, a field survey of several East Texas salamander species was conducted from October of 2022 through April of 2023 – during their peak activity season – to create an updated inventory of historic and anecdotal salamander populations previously reported at the Camp Tyler Outdoor School, a local non-profit field school for grades K-12, located in Smith County, Texas. All three target salamander species were observed and identified during this period, although current findings seem to indicate that some these animals, especially the previously documented population of Western lesser sirens (Siren intermedia nettingi) may have experienced significant population declines since they were last surveyed. This is likely the result of a variety of ecological factors that have changed over time, including an increased anthropogenic presence within the area, land use changes, possible degradations in water and habitat quality, changing climatic conditions, and out competition with more tolerant clades in their aquatic environment.

Date of publication

Summer 7-31-2023

Document Type

Thesis

Language

english

Persistent identifier

http://hdl.handle.net/10950/4255

Committee members

Brent R. Bill, PhD; Lance R. Williams, PhD; Ryan B. Shartau, PhD; Marsha G. Williams, MS

Degree

Master of Science in Biology

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