Effects of Burrowing Prairie Crayfish on Soil Nutrients and Microbial Communities.

North American crayfish (Family: Cambaridae) are considered keystone species in both terrestrial and aquatic invertebrate assemblages. Crayfish influence the flow of energy, nutrient cycling and perform important roles as predators, processors of detritus, vegetation and as carrion scavengers as well as being an important prey food for many higher animals in prairie ecosystems. There are six genus and 43 known species in the state of Texas of which four are primary burrowers. Terrestrial crayfish build “cone” shaped mounds that can reach 20 cm in height with burrows up to 2 m deep depending on the size of the crayfish and depth to the water table. This study described the distribution of terrestrial burrowing crayfish in a Blackland prairie environment by determining; 1) the relative abundance and density of terrestrial burrowing crayfish and 2) the chemical and biological properties of burrow excavations compared to the surrounding bulk soil. Water soluble C, total N and NH₄-N and NO₃-N and soil respiration were significantly higher in bulk soil than crayfish mounds. Incubations showed a significant decrease in N released from the crayfish mound than bulk soils suggesting reduced resources or lower or less active microbial communities in mounds. Microbial community analysis showed a significant reduction in signature PLFAs from 44 in bulk soil to 22 in mounds. These changes in PFLAs revealed significantly different communities between the bulk soil and crayfish mounds. Bacterial Fungal ratios declined by 40%, signature PLFAs for Actinomycetes declined 67% and protozoa 80%.