Freshwater Mussels Vary in Substrate Preference and Mobility in Pairwise Behavioral Experiments

Freshwater mussels are a highly imperiled group of organisms that are sensitive to environmental stressors such as drought, flooding events, and global warming. While most mussels are considered to have broad sediment tolerances, some species are micro-habitat specialists. Mussel mobility can vary between species, but few studies have tested this consistently under controlled conditions. The objective of this thesis was to use pair-wise substrate choice experiments to examine whether mussel substrate preference and mobility (horizontal and vertical) would vary in Central and East Texas mussels. This included testing 10 species under normal thermal conditions (Chapter I), as well as a case study on the effects of high temperatures on the common and abundant species Lampsilis teres (Chapter II). The goal of my first chapter was to test various hypotheses based on existing phylogenetic patterns, life history strategies, and mussel size. Behavioral responses were measured in two tank types over 72 hours, using approximately 50 individuals per species (407 total). Five of the 10 species significantly preferred sand over gravel, whereas three seemed to prefer gravel over sand, although the differences were not all statistically significant. Two species showed little to no substrate preference (Potamilus purpatus and Plectomerus dombeyanus). Some species (e.g., L. teres) moved horizontally ~22 times their body length, while some were immobile (e.g., P. dombeyanus). Substrate preference was consistent with previously proposed habitat preferences for 6 out of 10 species and most life history strategies. Individuals of smaller width tended to prefer finer substrate and burrow deeper. The results of the first chapter suggest that species can be classified along a gradient from broad substrate tolerance (i.e., generalists) to strong substrate preference (i.e., specialists), as well as a gradient of high and low horizontal and vertical mobility. The goal of my second chapter was to evaluate the influence of high temperature on the behavior of L. teres (a highly active species) at three temperatures (21, 28, and 34°C). In the medium treatment (28°C) the higher water temperature increased the general activity of mussels, an expected reaction as ectotherms. However, the highest temperature treatment (34°C) led to compromised vertical mobility, yielding the lowest number of individuals burrowed completely. Horizontal mobility tended to increase with temperature, and substrate preference for sand was weakest at 28°C. These studies provide insights into species-specific substrate preference and mobility of adult freshwater mussels, which is needed for conservation efforts such as relocation, re-introductions, and restoration in a changing global climate.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Aquatic Resources

Grantor

Texas State University

Year dc:date.issued

2023

Author dc:creator

• Martinski, Meghan

Advisor dc:contributor.advisor

• Schwalb, Astrid

Committee members dc:contributor.committeemember

• Aspbury, Andrea
• Robertson, Clint
• Hernandez-Abrams, Darixa D.

• freshwater
• mussels
• unionid
• behaviors
• habitats

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10877/18971

OAI identifier oai:identifier

oai:digital.library.txst.edu:10877/18971