La Blanca Island, the southeasternmost coral reef community in the Mexican Pacific

Abstract

Background. Corals and coral reefs of the eastern Pacific are distributed discontinuously from the Gulf of California to Huatulco, Mexico, and from Los Cóbanos, El Salvador, to northern Peru. The most southeastern coral community in the Mexican Pacific was Tejoncito (Huatulco Bays); however, recent surveys extend the distribution to La Blanca Island. Objective. To make known the characteristics, conditions, and fauna associated with the coral community of La Blanca Island. Methods. During 2016, surveys were conducted around La Blanca Island, where a small coral community was in the northern portion but not in the east and west. Results. The coral community is located at approximately 3 m depth and under a strong current; it is small and characterized by a relatively low coral cover (10 %) of the species Pocillopora damicornis, Pocillopora capitata, and Pocillopora verrucosa. Three coral species, 13 echinoderm species, and 50 fish species were recorded, all commonly associated with coral communities and reefs of the eastern tropical Pacific. The presence of corals on La Blanca Island is relevant because it corresponds to the most southeastern record in the Mexican Pacific (55 km East of Tejoncito, in the area of Huatulco Bays); the record is striking because it is located in a region with strong upwelling, high productivity, drastic changes in water temperature and low pH and Ωarag values, all of which are not very favorable for larval settlement, coral growth, and the development of coral communities. Conclusions. The current record not only broadens the spatial distribution range of corals and coral communities in the Mexican Pacific but also represents an opportunity to study the development of reef-building corals under harsh environmental conditions.