Crayfish Connections: Integrating Ecology and Hydrogeology in a Prairie Floodplain Using Burrowing Crayfish Distribution

Abstract:

Floodplain ecosystems are spatially heterogeneous, often encompassing lotic, lentic and ephemeral waterbodies that support high terrestrial and aquatic biodiversity. An understanding of species-habitat relationships within these intricate ecosystems could guide conservation efforts, but is lacking for many species, including for burrowing crayfish, a globally imperiled group whose members create aquatic-terrestrial connections via bioturbation of floodplain habitats. Because burrowing crayfish must burrow deep enough to access shallow groundwater in order to fulfill life history requirements, their pattern of distribution within a floodplain may signal the presence of select surface and subsurface characteristics. The first objective of our study was to determine if the distribution of active crayfish burrows was related to local abiotic factors, and our second objective was to assess how species composition at each sampling site varied with respect to those same factors. We evaluated crayfish presence (monthly from Jan.-Dec. 2017) and species composition (from collections made in spring 2018) in relation to groundwater depth, inundation duration, soil characteristics, and tree size at 75 sites in the Bogue Chitto Creek watershed in the Black Belt Prairie of Alabama. We hypothesized that the presence of burrowing crayfish would be associated with relatively shallow groundwater depths, fine-scale soil characteristics, and large trees, while the composition of species captured at each site would vary with groundwater depth and soil characteristics. Our study showed that the probability of observing active crayfish burrows was driven primarily by groundwater depth, with an increased likelihood that crayfish were present at sites with a shallow water table (groundwater depths ranging from 35-180 cm). Species composition was marginally associated with groundwater depth and inundation duration. Identifying local environmental factors required by burrowing crayfish will spur additional studies of local and landscape level floodplain biodiversity and help elucidate how ecology and hydrogeology can be integrated to craft productive management plans for areas that benefit multiple species.