The Distributions of Fish Populations in the Natural and Mitigated Mangroves Forests in Southeast Florida.

The purpose of this study was to compare the fish communities in mitigated and natural mangrove areas in the Port Everglades estuary. This study of fish recolonization of recently (ca. 5 years) planted mangrove forests, tested the null hypothesis that the species composition, size distribution and abundance of fish collected in natural, established and mitigated mangrove environments were the same. Two natural mangrove areas and two mitigated mangrove areas were used as study sites in John U. Lloyd Park. Two natural mangrove areas and two mitigated mangrove areas were used as study sites in West Lake Park. A variety of sampling gear types were utilized in the collection of fishes. Sampling was only done at low tide for all areas. Differences (chi square) in the abundances of fishes occurred between the natural mangrove sites in John U. Lloyd and West Lake Parks. These differences are thought to be due largely to differences in the hydrodynamic environment (i.e. tidal flushing, discharge rates of waterflow) and seasonality (i.e. month). However, differences between the fish communities in the mitigated areas of both parks were not significant at the 0.05 level of probability. Small fishes, the forage base for the larger piscivores, were equally represented in the mitigated sites throughout the study, and always dominated their respective communities numerically. Differences between natural and mitigated mangrove areas occurred in the distributions of transient species. In general, these transient fishes occurred only in the natural sites: the larval stage of one transient species, however, was found only in the mitigated sites. Likewise, within a species, smaller fishes were generally found in the mitigated sites and larger fishes were found in the natural sites. Thus, differences in the distributions of fishes between the mitigated and natural mangrove sites may be due to food availability as well as structural differences (i.e. spacing of plants) in each habitat. This study shows that mitigated mangrove forests are suitable habitats for small, forage species and presently there are differences in the fish populations in the natural and mitigated mangrove environments, the largest mangrove ecosystem remaining in Broward County