Beta-diversity of macroinvertebrates associated to Pocillopora corals along the Mexican Pacific coast

Abstract

Although invertebrates are the most diverse organisms associated with corals, they have been poorly studied in the Eastern Tropical Pacific. Thus, this study analyzed macroinvertebrate assemblages associated with Pocillopora corals along the Mexican Pacific coast and assessed whether a latitudinal diversity gradient can be identified. Forty-two sites grouped in 12 localities were sampled by visual censuses from the southern Gulf of California (26° N) to the coast of Oaxaca (15° N). Ecological indices (species richness, abundance, and taxonomic distinctiveness) were compared among localities. A Bray–Curtis resemblance matrix was also created, and a non-metric multidimensional scaling (nMDS) was performed to identify locality groups based on macroinvertebrate abundance and occurrence. Beta-diversity as a measure of the proportional species turnover was determined in each locality group. A total of 129 species grouped in six phyla were recorded. All the ecological indices differed significantly among localities. Five groups that moderately followed a geographic pattern were formed by nMDS. Nevertheless, no evidence of a beta-diversity latitudinal gradient was found. Beta-diversity calculated in each group indicated that the central region of the Mexican Pacific and the Gulf of California have the highest species proportion in the studied area. Furthermore, the composition of macroinvertebrate assemblages had a “turnover and nestedness” beta-diversity pattern. These results are very useful for conserving species richness associated to coral communities along the Mexican Pacific coast. Establishment of marine protected areas in locality groups with a high macroinvertebrate beta-diversity should be considered, especially when harmful human activities can affect it negatively.