Multi-scale spatial and partitioning analyses of the reef-fish community composition of the Yucatan fringing reef system

Coral reef and reef-fish communities are complex systems that have spatial structures that are influenced by multiple factors and processes that interact at several scales. We analysed composition data of reef-fish communities in the Yucatan Peninsula fringing reef system using a hierarchical multi-scale survey design to elucidate the origins of the species distribution patterns through multivariate canonical ordination and partitioning analysis. Twelve reef sites were surveyed along the fringing reef system, nested in three sectors, each with distinctive human interests (tourism, fishing, protection). Line transects were placed on reef lagoon, reef front, reef slope and reef terrace habitat for a total of 480 transects. The communities were composed of many rare and some dominant species (e.g., Thalasoma bifasciatum, Acanthurus bahianus, A. coeruleus, Sparisoma aurofrenatum). Redundancy analyses revealed that environmental variables explained between 11% and 22% of the variation in fish community data according to the habitat analysed. Spatial variables, represented by the geographic coordinates of transects, explained a low percentage (2-5%) of variation in the fish community data. Among the environmental variables that significantly explained (P < 0.05) the patterns of variation on the fish community were depth, topographical complexity, and the percentage of the substratum covered by algae, calcareous floor, rock and rubble. Although the total explained variation and proportion of the variation explained by each set of variables were consistently low, most of the effects on the fish community composition data were significant. Explanations are proposed concerning those results. Evincing the distribution patterns on the biological systems of multi-species as well as the causes that shape them is key for conservation planning and essential in highly threatened regions, such as the Caribbean coast of the Yucatan Peninsula.