Date of Award

December 2020

Document Type


Degree Name

Master of Science (MS)


Environmental Engineering and Earth Science

Committee Member

Catherine M. Bodinof-Jachowski

Committee Member

Stephen F. Spear

Committee Member

Robert F. Baldwin


The Carolina Heelsplitter (Lasmigona decorata) is a federally endangered freshwater mussel endemic to North and South Carolina, USA. The species has experienced dramatic range-wide declines as a result of habitat fragmentation and water quality deterioration, and the remaining populations are isolated and extremely small. Conservation efforts for the Carolina Heelsplitter have been limited by a lack of knowledge regarding distribution, life history traits, and habitat requirements. Our objectives during this project were to 1. Evaluate the efficacy of an environmental DNA (eDNA) assay to detect the Carolina Heelsplitter and a known host fish, the Bluehead Chub, from stream water samples and 2. Develop a biotic integrity index to assess habitat suitability within three ecologically important watersheds.

To determine if eDNA techniques can be used to detect the Carolina Heelsplitter and the Bluehead Chub from stream water samples, we developed species specific primer pairs and probes for the target taxa and applied our assay to water samples collected from 100 randomly selected sites. While our assay validation successfully detected the Carolina Heelsplitter in stream segments where the species was known to occur, our results were highly variable, and we failed to detect the species at any new locations within the study area. Detection rates for the Bluehead Chub were high, indicating that host fish availability is relatively widespread within the study area and likely not a limiting factor in Carolina Heelsplitter recruitment. Our results suggest that current eDNA sampling methods may be ineffective for some extremely rare unionid taxa.

To assess habitat suitability, we developed a predictive model of macroinvertebrate biotic integrity based on samples collected across 49 spatially balanced sites. We used multiple linear regression and model ranking criteria to evaluate potential drivers of biotic integrity at multiple spatial scales. We found that local stream conditions were influenced by a relatively large spatial extent, and that land use immediately adjacent to the stream edge plays a larger role in determining biological condition than land use across the entire upstream watershed. Our results can be used to identify areas of high and low habitat quality, evaluate connectivity between populations, and prioritize locations for reintroducing propagated mussels.



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