The Use of Biomonitoring Data to Inform Species Distributions, Habitat Associations, and Threats
Biomonitoring is a periodic and systematic quantification of species numbers, abundances, or densities and the species-associated environments. As a stipulation of U.S. Fish and Wildlife Service (USFWS) incidental take permit, a biomonitoring program was established in the upper reaches of the San Marcos and Comal rivers (TX) in 2013 to monitor incidental take of the federally endangered Fountain Darter Etheostoma fonticola. The purpose of this study was to evaluate the biomonitoring program over a 9-year period (2014 – 2022) for the benefit of discovering new insights into Fountain Darter ecological relationships and potentially for refining the program for the upcoming incidental take permit renewal. Study objectives were to quantify spatial and temporal patterns in Fountain Darter densities, flow-density relationships, recreation-density relationships, and habitat associations of the Fountain Darter among three reaches of the San Marcos River and four reaches of Comal River in wadeable habitats and in non-wadeable habitats with each reach and habitat type representing a semi-independent observation. Among some of the more significant findings, Fountain Darter densities were greater in the upper most reaches of each river than in the lower reaches, densities varied through time with some reaches indicating increasing and decreasing population trends, and densities were largely unaffected by flows, which ranged from low flow events during an extreme drought to small flood events during wet years. Non-wadeable reaches with high amounts of instream recreation had lower densities of Fountain Darters than non-wadeable reaches with low amounts of instream recreation. Density distributions were used to establish density thresholds (low, moderate, and high condition) for qualitatively communicating the health of Fountain Darter populations, which represents an example of using biomonitoring data as a context to interpret future biomonitoring data. With more species being listed by USFWS, the number of incidental take permits will undoubtedly increase; therefore, evaluation of existing biomonitoring programs can lead to improved designs in biomonitoring protocols.
biomonitoring, species, distributions, habitat associations, threats, endangered species
Wolter, M. (2023). The use of biomonitoring data to inform species distributions, habitat associations, and threats (Unpublished thesis). Texas State University, San Marcos, Texas.