ABSTRACT
Only two long-term, quantitative studies of Everglades freshwater fishes have been conducted, both in the E leocharis marshes of the southern Everglades within Everglades National Park. Each study attempted to describe the dynamics of the fish community with relation to hydrological conditions in the marshes. The earlier study, using pull-trap data from 1966 to 1972, has been published and widely cited; these data have been reanalyzed for comparisons in this chapter. In the second study presented here, fish data obtained from the pull traps were compared with those from throw traps to re-evaluate the conclusions of the original pull-trap study. The two long-term studies produced contradictory conclusions about the responses of small fishes to periods of prolonged flooding. The throw-trap results showed that annual mean densities of small fishes increased across the 1977-85 study period when the marshes did not dry. There was no evidence that predation by large fishes caused a reduction in small-fish densities during high-water periods. It is likely that small fishes use the densely vegetated marshes as refuges from predation. Fish community composition in the marshes did not shift from small to large species but remained stable. Shifts in assemblage dominance in the Everglades marshes may occur coincidentally with long periods of water level stability, but not within the temporal scale of the authors’ study. The comparisons of pull-trap and throwtrap data sets collected concurrently demonstrate that pull-trap data do not accurately reflect small-fish community dynamics. Biases associated with the pulltrap method explain the conclusions of the first long-term study. The impacts of repeated drydowns on marsh fish communities are discussed, and the implications for marsh restoration are presented.
