Scaling up beta diversity on Caribbean coral reefs

The objective of this paper is to find good proxies that are important to explain the spatial variation of beta/delta diversity in coral reefs. To reach that objective, we looked for and identified the environmental and spatial variables most strongly related to variation in fish and coral species richness and composition. We studied variation in fish and coral species diversity at two spatial scales: among geomorphology classes (reef lagoons, fronts, slopes and terraces) within reefs (beta diversity), and among eleven reefs across a 400-km latitudinal diversity gradient (delta diversity) in the western Caribbean Sea. The variation of species richness and community composition was partitioned between environmental and spatial variables. Two-way ANOVA (for richness) and MANOVA (for presence-absence community composition) were used to test for the influence of reefs and geomorphology classes on fish and coral species richness and community composition. The results show that for both fish and coral, differences among geomorphology classes were strong whereas there were no significant differences among the reefs. We identified additional spatially-structured environmental variables that explained the spatial variation of fish and coral species richness and community composition at the various scales. Geomorphological structure, “reefscape” attributes at different scales, and depth are important variables for shaping beta/delta diversity. We discuss the impact of our results with respect to regional ecomanagement strategies and the creation of marine reserves.