The relationship between reef fish community structure and environmental variables in the southern Mexican Caribbean

Abstract

The reef fish community of the Mexican Caribbean and the factors governing its structure are poorly known. Using canonical correspondence analysis (CCA), the relationship between fish community species composition and abundance, and environmental variables was investigated at three Mexican Caribbean reefs. These reefs are separated by c. 70 km: Boca Paila, located in the northern Sian Ka'an Biosphere Reserve; Tampalam, in the southern portion of said reserve; and Majahual, an unprotected area near the Mexico/Belize border. One hundred and thirty-four fish species belonging to 41 families were identified by underwater visual census. Their quantitative data, and 15 environmental variables collected during 60 sample transects, were analysed. The sample stations were distributed among the three reefs, and covered five dominant habitat types: reef lagoon, back reef, reef crest, reef front and reef slope. The variables estimated were: temperature, depth, current direction, current intensity, vertical relief, visibility, topographical complexity and substratum coverage (percent of sand, seagrass, algae, rock and rubbles, gorgonians, massive coral, branching coral and encrusting coral). Ordination diagrams with points based on fish species, sample sites, and environmental variables, showed a pattern mainly determined by degree of reef site complexity. Habitat scale environmental factors defined element distribution in three main areas: (a) reef fish species associated with lagoon and back reef sites of low topographical complexity; (b) species associated with intermediate complexity reef crest sites; and (c) species associated with high complexity reef front and reef slope sites. Nearly 52% of the variation in fish species data was explained by environmental variables in the direct and simultaneous ordination analysis. Topographical complexity was the most important variable, but depth, encrusting coral coverage, and vertical relief also had significant effect on fish species. Use of multivariate statistical methods proved valuable in deciphering the reef fish community structure patterns in the southern Mexican Caribbean. The current study provides a base for future reef fish research and regional tourism and fisheries management. © 1998 The Fisheries Society of the British Isles.