Posthurricane Recovery of Riverine Fauna Reflected in the Diet of an Apex Predator

Abstract

Hurricane Charley, a category 4 storm on the Safford–Simpson scale, passed over the Peace River, Florida, and its watershed on 13 August 2004 causing widespread hypoxia. An electrofishing study investigating the abundance of the euryhaline Centropomus undecimalis (common snook) began in the freshwater portions of the Peace River 3 months after the storm (November 2004) and included diet sampling. Samples were taken seasonally up to August 2006. Changes in the prey assemblages of C. undecimalis determined through multivariate analyses (e.g., nonmetric multidimensional scaling) were used as a proxy to estimate the recovery of riverine fauna. The initial posthurricane prey assemblages were dominated by species well adapted to low dissolved oxygen, namely Gambusia holbrooki and Hoplosternum littorale. A significant long-term serial change in assemblage structure occurred as the abundance of G. holbrooki and H. littorale decreased and other river fauna such as Procambarus spp. and ictalurid catfish increased. Assemblages were presumed as recovering 1 year after hurricane landfall, a posthurricane recovery period that is an order of magnitude longer than those reported for estuarine fish assemblages. The approach of using stomachs as sampling tools detected changes at the assemblage level that included an armored catfish species (e.g., H. littorale) and cryptic invertebrate species (e.g., Procambarus spp.) that went unnoticed in a study using standard electrofishing methods. Although sampling the diet of C. undecimalis was useful in detecting assemblage-level changes, other metrics—such as changes in health, sex ratio, relative abundance, and juvenile year-class strength of fishes and invertebrates collected by traditional fishing methods—are needed to fully evaluate the effects of the hurricane. Nonetheless, this study demonstrates that diet studies can supplement standard fishery gear to create a more comprehensive sampling strategy for aquatic fauna.