Fish Community and Trophic Structure at Artificial Reef Sites in the Northeastern Gulf of Mexico

Fish community and trophic structure were examined quarterly from fall 2004 through spring 2007 at 27 artificial reef sites located 15-20 mi south of Pensacola, Florida. Location of study sites was not reported to the public when reef modules were deployed in 2003, thus sites were presumed to be unfished. Community structure estimates were derived from video sampling that was performed with a micro remotely operated vehicle (ROV) equipped with a laser scale to estimate fish size. A total of 81,207 individuals from 77 different taxa was enumerated from video samples. Fish assemblages were dynamic in species richness, fish community structure, and trophic structure across time and by reef design. Total fish density, biomass, and species richness increased across time. Red snapper, Lutjanus campechanus (Poey, 1860), was by far the most abundant species (29% of individuals, 45% of total biomass), and its density and biomass increased over the course of the study. Differences in fish community structure were driven by sharp declines in grouper abundance and the proliferation of smaller fishes across time. Trophic structure was consistently dominated by invertivore/piscivores, while fluctuation in piscivore biomass and increased abundance of planktivores drove differences in trophic structure. Size distributions for many fishery species known to display low annual site fidelity were composed primarily of young, sub-legal individuals. Disappearance with increasing fish size was likely due to shifting ontogenetic habitat requirements or exposure to high regional fishing mortality for species that displayed low annual site fidelity to study sites.