Predation, habitat complexity, and distribution of the crayfishProcambarus alleni within a wetland habitat mosaic

Abstract

The crayfishProcambarus alleni is abundant in densely vegetated habitats within the freshwater wetland mosaics of central and southern Florida. We performed laboratory experiments to determine whether habitat preference and/or predation could account for habitat use by this species. First, groups of crayfish were placed into tanks divided evenly into vegetated and non-vegetated sides, and habitat use was measured during the day and night. Crayfish preferred vegetated habitats during both the day and night, although use of non-vegetated habitats increased significantly at night. Next, different size classes of crayfish were exposed to predatory largemouth bass (Micropterus salmoides) in experimental tanks of varying habitat complexity (i.e., plant biomass). Bass reduced survival of small-sized crayfish but had no effect on larger crayfish. Larger crayfish also seemed to prey upon smaller crayfish. Susceptibility of crayfish to predation decreased with increasing habitat complexity. Experimental results are consistent with field observations and indicate that predators and habitat complexity play important roles in determining the distribution and daily activity ofP. alleni within wetland habitat mosaics.