North America is home to 302 unionoid species, with approximately 53 occurring in Texas, and are considered one of the most imperiled group of organisms in North America. Several hypotheses have been proposed to explain the spatial distribution of mussels within a stream reach, but only certain hydraulic characteristics appear to be correlated with their distribution. Emerging evidence indicates that freshwater mussels may use flow refugia to remain embedded during high flow events. As the use of hydraulic variables to characterize mussel habitat becomes more widespread, it may be useful to implement sampling that captures these measures. One option may be a Basin Visual Estimation Technique (BVET) that utilizes classification by riffles, pools, and runs. I sampled populations of freshwater mussels using this three-tiered sampling scheme in order to investigate habitat associations.

I sampled 31 sites along the upper Neches River in Texas through excavating 0.25m2 quadrats for mussels and the collection of site specific environmental data at the same location. Three-way log-linear contingency tables and canonical correspondence analysis was used to elucidate if associations between species, environmental characteristics, and mesohabitats were occurring. The results suggest that numerous species do associate with mesohabitats and are associated with certain environmental characteristics and areas of low shear stress. For example, the Louisiana Pigtoe (Pleurobema riddellii) was found to associate with run habitats that contain gravel substrate as the subdominant substrate. Implementing sampling protocols that use classification by mesohabitats may help managers determine habitat associations for a wide array of freshwater mussels.

Date of publication

Summer 8-8-2017

Document Type




Persistent identifier


Committee members

Dr. Neil Ford, Dr. Lance Williams, and Dr. Jon Seal


Masters in Biology