The Carolina Heelsplitter (Lasmigona decorata) is a critically endangered freshwater mussel endemic to North and South Carolina. Because of its rarity, there is a deficit of information regarding the specific habitat requirements for colonization and persistence and where suitable habitat may exist. Understanding these requirements is essential for determining factors driving species decline and for guiding future management and restoration efforts. As part of an ongoing study, we developed a quantitative PCR assay to quantify the presence/absence of the Carolina Heelsplitter and a known host fish throughout the Upper Lynches River sub-basin in South Carolina. We will collect water samples during March of 2019, coinciding with the spring release of mussel larvae by gravid females. We will collect replicate water samples to account for imperfect detection and negative controls to monitor for potential contamination. We will investigate occupancy and detection probabilities as functions of environmental covariates, such as water chemistry, channel morphology, riparian characteristics, and land use attributes. Our preliminary results, which include controls and initial field samples, demonstrate the utility of eDNA as a highly sensitive survey tool, despite the extremely low density of the target species
