Spatio - Temporal Variation in Crayfish Production in Disturbed Marl Prairie Marshes of the Florida Everglades

We used the burrowing crayfish Procambarus alleni as a model organism to compare spatial and temporal patterns of density, standing crop biomass, and sizestructured productivity in the seasonal wetlands of the Florida Everglades where environmental stress has been exacerbated by hydropattern disturbance. Crayfish density was not linked to fluctuations in water temperature or dissolved oxygen and was only artifactually associated with water depth. Density and biomass within sites were similar over time but increased significantly in habitats with longer hydroperiods (duration of flooding). The effect of hydroperiod-associated habitat quality on annual crayfish production, in terms of size-structured growth and recruit production, was even more pronounced. Crayfish production in the long-hydroperiod sites was approximately two times greater than in medium-hydroperiod sites and five times greater than in shorthydroperiod sites. Turnover ratios (productivity:biomass) showed that the spatial trend in productivity consistently lagged density and biomass trends in the shorter hydroperiod habitat, indicative of population sink conditions. The long-hydroperiod sites were characterized by high productivity and appeared to function as population sources from which crayfish dispersed to nearby, often marginal, habitats. Therefore, the spatial extent and distribution of short-hydroperiod sink habitats significantly impacted crayfish density, population size structure, and productivity. Simple estimates of density or biomass that do not account for the influence of hydropattern on habitat quality may be misleading indicators of productivity because survival, growth, and reproductive output may vary substantially across disturbed landscapes.