SPATIAL ECOLOGY OF THE CRAYFISH PROCAMBARUS-ALLENI IN A FLORIDA WETLAND MOSAIC

We investigated patterns of differential habitat occupation by the cra yfish Procambarus alleni, a numerically abundant and trophically impor tant species in freshwater marsh systems of southern Florida. Crayfish were collected from emergent wet prairies and sloughs in marshes form ing the headwaters of the St. Johns River, Florida between August 1992 and December 1993. In addition to differences in plant species compos ition, wet prairies had greater plant biomass and lower water depths t han sloughs. Mean density and biomass of crayfish were significantly h igher in the densely vegetated wet prairies (28 per m(2); 26.9 g per m (2)) than in aquatic sloughs (3 per m(2); 1.5 g per m(2)). Crayfish de nsity increased with increasing plant biomass (i.e., habitat complexit y) in wet prairies, whereas crayfish density decreased with increasing water levels (i.e., hydroperiod) within slough habitats. Recruitment occurred throughout the study, and the majority of crayfish collected were small in size (< 1.0 g). Ovigerous females were rarely collected and were found only in wet prairies. Differences in relative risk of p redation, food availability, or a combination of these factors are lik ely generating differences in habitat occupation by the crayfish P. al leni in this wetland habitat mosaic. Efforts to restore and manage fre shwater marshes in southern Florida (e.g., Everglades, Lake Okeechobee , Kissimmee River, St. Johns River) would benefit by considering spati al aspects of the ecology of indicator taxa such as crayfish.