Fish Assemblages in Three Northwest Florida Urbanized Bayous before and after Two Hurricanes.

A 6-year survey (1993-1998) is summarized for fish collected from chemically contaminated, urbanized bayous in northwest Florida. Fifty-two monthly collections (January-November) using trawls and seines occurred at 22 sites located in three adjacent bayous associated with the Pensacola Bay Estuary. Hurricanes Erin (Category 2) and Opal (Category 3) made landfall near the study area, and a state-wide entanglement net ban was initiated during the survey period. Approximately 585,000 fish were collected, which represented 80 species and 66 genera. The assemblages were dominated by estuarine-dependent and resident species similar to those commonly found in several nearby estuaries. Of these, Leiostomus xanthurus, Brevoortia patronus, Anchoa mitchilli, Lagodon rhomboides, and Menidia peninsulae composed 95% or more of the total catch. The total number of species for each collection ranged from 8 to 23, total abundances varied from 140 to 14,315 individuals, and Shannon diversity index values (H9) were between 0.02 and 0.97. Mean species numbers and diversity index values were more consistent monthly than fish total abundance, which was influenced by seasonal occurrences of estuarine-dependent species. Hurricane effects were specific to the hurricane, structural parameter, species, and bayou. The posthurricane reductions in salinity (17% to 69%) and the few changes in fish abundance were usually temporary and within monthly and interannual variability. The resiliency of the fish assemblages to natural and anthropogenic stresses represents a survival advantage and readiness for future climatic change. [ABSTRACT FROM AUTHOR]