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In coral communities, herbivorous fish play a major role in maintaining and controlling algae, which are the base of the food chain in coral reefs. Among the herbivorous fish of coral reefs, the family Acanthuridae is one of the most abundant. Effects of this family on coral reefs can vary depending on their densities, ecosystem stability, and their interactions; therefore, determining the status of their populations is a concern. In the archipelago of San Andrés, Providencia, and Santa Catalina (ASAP) there is a lack of information on the status of the abundances and densities of this group. Through visual censuses of species of the genus Acanthurus, the population states in the ASAP coral communities and the population differences between the evaluated sites (San Andrés, isla cayo Bolívar, isla cayo Serrana and Providencia) were estimated. Showing an abundance of 6075 individuals, in addition to a positive relationship of abundances in the islands of San Andrés and Providencia with respect to the Bolívar and Serrana keys. Regarding the habitat preference of juveniles, a specialization and habitat preference of A. coeruleus was found for reef zones, while A. tractus showed a preference for mangroves. [ABSTRACT FROM AUTHOR]

The abundance of the most common fishes of a fringe reef at Havana City was estimated using monthly visual censuses from 2001 to 2003. The site was divided in five biotopes according to bottom characteristics. Five random sampling units of 25 m² were defined on each biotope using a square frame. All the fishes of the species Stegastes partitus (Poey, 1868), Thalassoma bifasciatum (Bloch, 1791), Halichoeres bivittatus (Bloch, 1791) and Acanthurus bahianus (Castelnau, 1855) were counted. Most of the species had it's maximal abundance on the rainy season and at 12-15 m depth. Stegastes partitus and Thalassoma bifasciatum were the most abundant species and they had two abundance maxima: one in February and other in June and August respectively. Halichoeres bivittatus juveniles predominated at the 15m depth and the adults were at 3m depth, which suggest that this species spawns in shallow waters and the settlement of juvenile, after the larval stage, occurs at deeper waters. Acanthurus bahianus was the less abundant species of those included in this study. [ABSTRACT FROM AUTHOR]