Effects of burrowing prairie crayfish on soil nutrients and microbial communities.

• In Event: Terrestrial Ecology & Management Oral Session 1

Abstract

North American crayfish (Family: Cambaridae) are considered keystone species in both terrestrial and aquatic invertebrate assemblages. Crayfish influence the flow of energy and nutrient cycling as well as supporting many higher animals in prairie ecosystems as prey food. Crayfish also perform important roles as predators, processors of detritus, and scavengers of carrion and vegetation. In Texas, of the six genera and 43 known species only four are considered primary burrowers. Terrestrial burrowing 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 compared to crayfish mounds. Soil incubations exhibited 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 using phospholipid fatty acids (PLFAs), showed a significant reduction of biomarkers 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 biomass ratios declined by 40% while biomarker PLFAs for Actinomycetes and Protozoans declined 67% and 80%, respectively.

Authors

• Tara Nawrocki, Texas A&M University - Central Texas

• Harold P. Collins, USDA-ARS

• Philip Fay, USDA-ARS

• Wayne Polley, USDA-ARS