Reef fish communities associated with Acropora palmata:: Relationships to benthic attributes

Reef benthic attributes such as topography, substrate diversity, and live coral cover have all been correlated with reef fish abundance, diversity, and distribution. In this study, I examine the role of the branching coral Acropora palmata as habitat for reef fishes in Florida and the U.S. Virgin Islands. By contributing both significant coral cover and topography to shallow reef environments, A. palmata can have a major influence on the abundance and diversity of reef fish populations. Fish populations were surveyed in a two-factorial design to determine the effects of coral cover and reef topography on fish abundance and diversity. Within a single reef, four habitat types were sampled: (1) High Topography/High Coral Cover, (2) High Topography/Low Coral Cover, (3) Low Topography/High Coral Cover, and (4) Low Topography flow Coral Cover. Areas dominated by live A. palmata had significantly higher abundance of damselfishes, grunts, and snappers compared to other reef areas without this coral species. Other groups, such as parrotfishes, surgeonfishes, and wrasses, were abundant in areas with low topography and high cover of macroalgae. Fish schools composed mainly of grunts and snappers were found almost exclusively around live or dead A. palmata colonies. The high topography provided by A. palmata was the main factor affecting fish distribution and abundance. However, coral cover can be a significant factor for selected fish groups. The presence of significant interactions between the factors tested, as well as conflicting results from previous studies, suggest that it is unlikely that reef fishes respond directly to a single environmental gradient in predictable fashion.