Effects of the 2004 hurricanes on the fish assemblages in two proximate southwest Florida estuaries: Change in the context of interannual variability

We examined interannual differences in fish assemblage structure in Tampa Bay and Charlotte Harbor, Florida, from 1996 to 2005 to reveal the extent of hurricane-induced changes in relation to multiannual variability for five different assemblages in each estuary: small-bodied fishes (<generally 80-mm standard length) along river shorelines, in river channels, along bay shorelines, and on the bay shelf (<1.5-m water depth); and large-bodied fishes (>generally 100-mm standard length) along bay shorelines. Fish assemblages tended to differ, between estuaries, as did interannual variability in assemblage structure. In the lower portions of tributary rivers to Tampa Bay, the small-bodied shoreline fish assemblage during August 2004 to July 2005, i.e., during and after the multiple hurricanes, was different from assemblages of August to July in previous years. This may have been a result of physical displacement of fish or suboptimal salinities caused by increased freshwater inflow. The small-bodied shoreline fish assemblage in Charlotte Harbor also differed between prehurricane and hurricane periods, possibly because damage to vegetated shorelines affected fish survival through a decrease in feeding and refuge habitats. In the remaining habitats, fish assemblage structure from August 2004 to July 2005 were within the range of variability exhibited over the 9-yr study period. There were several unusual fish assemblages that appeared to be attributable to drought conditions (1996, 1999–2000), suggesting that other major environmental perturbations may be as important as hurricanes in influencing assemblage structure. We conclude that although the 2004 hurricane season affected some of the fish assemblages of Tampa Bay and charlotte Harbor, these assemblages generally appeared quite resilient to natural environmental perturbations from a decadal perspective.