Where the crawdads sing: Modeling crayfish abundance in relation to abiotic and biotic factors in eastern-deciduous forest streams

Crayfish (infraorder Astacidea) are a keystone species in their freshwater habitats, influencing ecological functioning. While habitat degradation and non-native crayfish invasions become an increasing threat to crayfish populations in the southeastern United States, researchers have yet to fully understand crayfish life history, behaviors, and ecosystem roles. Effective conservation will require a better understanding of crayfish ecology, and current knowledge gaps are the primary barrier to successful efforts. In our study, we address the lack of biological information about crayfish populations by investigating the physical, spatial, and organismal drivers of their abundance. Our study focuses on eight small, forested streams, each sampled along four 5-m transects (transects), in the Virginia Coastal Plain, including sites in Williamsburg and James City County. We related crayfish abundance to predictors on the basis of Generalized Linear Mixed Modeling (GLMM). Crayfish presence was detected at 30 of the 32 transects, with an abundance ranging from 1 to 27. Crayfish abundance had a positive association with summer months, water volume, and water temperature, and a trend for a negative association with phosphate concentration, but not percent oxygen, nitrate + nitrite, and leaf litter. Our study increases the understanding of the ecology and habitat use of crayfish to better inform conservation efforts.