Mussel community and changes in water quality within a southcentral river basin of North America with emphasis on two federal candidate species
Schoeck, Caitlin N.
Louisiana Pigtoe Pleurobema riddellii and Texas Heelsplitter Potamilus amphichaenus are candidates for listing by the USFWS under the Endangered Species Act and recognized as functionally extirpated within the Sabine River basin of Texas and Louisiana. Threats to range-wide population viability include changes in water quality. Purposes of this study were to update current knowledge of Louisiana Pigtoe and Texas Heelsplitter occurrences, catch-per-unit effort (CPUE), and habitat associations and to assess changes in Sabine River basin water quality over a 50-year period. A total of 9,244 individuals, representing 28 species, were identified and enumerated among five reaches (two mainstem reaches, three tributary reaches) and 46 samples. Mean CPUE (± 1 SD) per species among all reaches ranged from 0.01 (0.04) mussels/person hour (p-hr) to 10.4 (21.1) mussels/p-hr. Louisiana Pigtoe (N = 57) and Texas Heelsplitter (N = 7) were only observed in the upper Sabine River with a mean CPUE of 0.51 (± 1.68) mussels/p-hr for Louisiana Pigtoe and 0.06 (± 0.20) mussels/p-hr for Texas Heelsplitter. Louisiana Pigtoe was associated with mid-channel, riffle and run habitats with swift current velocities, shallow depths, and gravel substrates. Texas Heelsplitter, based on a small sample size, was associated with mid-channel, riffle habitats with swift current velocities and shallow depths and sand and gravel substrates. Between 1960/1970s and 2020s, water quality variables generally improved when referencing water quality standards deemed suitable for aquatic life use within the Sabine River basin. One exception was noted in two reaches with recent elevation in sulfates. Between 1960/1970s and 2020s, information on mussel occurrences and CPUE are lacking to assess trends in mussel communities. Nevertheless, mussel community and water quality data provided herein will provide baselines for future monitoring of the mussel community.
endangered species, Sabine River
Schoeck, C. N. (2023). Mussel community and changes in water quality within a southcentral river basin of North America with emphasis on two federal candidate species (Unpublished thesis). Texas State University, San Marcos, Texas.