| The Everglades is a unique ecosystem that has been fundamentally altered in the last seventy years. The system of connected sloughs, marshes, and wet prairies were drained to promote agriculture and urbanization. Because the drainage of the Everglades has affected the aquatic fauna, understanding the faunal response to hydrology is a necessary and important step to the restoration process. Because previous reports of crayfishes in Everglades National Park (ENP) only listed the Everglades crayfish (Procambarus alleni), archived samples of crayfishes from 1980 to 1998 were examined after identifying a second species, slough crayfish (P. fallax) in study sites. Everglades crayfish were dominant when wetland drying was frequent, whereas slough crayfish dominated when drying was infrequent. Differential tolerances to dry-down frequency were manifested in species-specific vital rates. Everglades crayfish population dynamics were limited by low recruitment in flooded years, whereas slough crayfish population dynamics were regulated by low rates of survival in drying events as short as two weeks. To investigate the spatial ecology of two crayfish species in the Florida Everglades, I constructed two types of spatially explicit models. First I constructed a cellular automaton model to investigate the importance of neighboring cells on the probability of colonization. The influence of neighbors was approximately zero for the Everglades crayfish, whereas the effect for the slough crayfish could not be determined from these data. Second, I constructed a spatially explicit population model in a Bayesian framework (uncertainty in parameter estimates) for slough crayfish under two hydromanagement alternatives. Prior information was derived from a literature review of crayfish survival and laboratory growth data. A priori expectations of parameter values were updated by fitting a two-stage model to trends in abundance. Mean values of the posterior densities on population dynamics parameters were used to estimate a probability density for dispersal between grid cells. Because a Bayesian framework was used, model performance measures (density m −2) were conveyed with uncertainty. The hydrologic alternative that decreased the severity and extent of dry down events (Comprehensive Everglades Restoration Plan) had higher densities m−2 than a base scenario that had no hydrologic modifications to the current system. |
