A multi-method approach for conserving a rare, burrowing North American crayfish (Cambarus causeyi)

The Boston Mountain Crayfish, Cambarus causeyi, is classified as a Species of Greatest Conservation Need in Arkansas, United States of America, and is endemic to the Ozark Mountains of North America. The relatively small range and rarity of this species makes it vulnerable to extinction, and the species has knowledge gaps that need to be addressed to facilitate conservation. We utilized species distribution modeling (SDM) using the program MaxEnt and fine scale habitat modeling to analyze the distribution and habitat preferences of C. causeyi. Our SDM found average annual precipitation was the most important predictor of C. causeyi presence. We collected habitat data from across C. causeyi’s known range, and we used fine scale-data to ground-truth our SDM. We detected C. causeyi at only nine of 51 sites, potentially due to sampling outside of the peak of the reproductive season. We ran our fine-scale analysis by modeling zero-inflated Poisson generalized linear models and selecting most-supported models with AICc. Our best model included proportion of sand in the soil and the presence of a competing burrower as explanatory variables. The MaxEnt output was found to be a poor predictor of finding C. causeyi in our fine-scale analysis, potentially because the SDM did not account for biotic interactions and lacked accurate soil data. We also developed an environmental DNA (eDNA) assay for the detection of C. causeyi and tested it across a subset of our field sampling sites. Cambarus causeyi eDNA was found at 24% of sites, a higher percentage of sites than we were able to detect C. causeyi from using conventional field sampling. Our findings are promising for future applications of eDNA to C. causeyi population monitoring.