MEPS 467:89-96 (2012)  -  DOI: https://doi.org/10.3354/meps09950

ABSTRACT: We tested the hypothesis that coral assemblages along the Florida reef tract have recently become more biologically homogeneous than they were in the past. We used a database that consisted of a probabilistic, 2 stage, stratified-random survey design to assess the condition of stony corals every summer from 2005 to 2010. At each of the 1176 sites in 9 putative subregions, examined over the 6 yr period, all coral colonies >4 cm were identified to species and their diameters were measured within replicated 10 m² belt transects. This approach provided detailed spatial information on the species composition and size-frequency distributions of coral assemblages. Coral assemblages showed a nested relationship, decreasing in diversity and abundance north of 25°40’N. A comparison with previous studies suggested that major declines in recent decades in the primary reef-building corals Acropora palmata, Acropora cervicornis, and Montastraea spp. have homogenized assemblages across depths and reef zones. Of the 9 putative subregions, 6 were found to be redundant on the basis of coral composition. Florida’s reefs currently support a simpler coral assemblage than they did in the past, dominated by a small number of eurytopic, generalist species. The assemblages may be more stable now than during the previous several decades, but there has been a fundamental change in their composition and function. Through loss of the dominant reef-building coral species, the reefs of the Florida reef tract have lost the capacity to construct reef framework.

KEY WORDS: Biotic homogenization · Coral reef · Florida reef tract · Florida Keys · Corals