Opisthobranch Assemblages from a Coral Reef System: : The Role of Habitat Type and Food Availability

• Autores: Laura Sanvicente-Añorve, Margarita Hermoso Salazar, Jazmín Ortigosa, Vivianne Solís-Weiss, Elia Lemus-Santana
• Localización: Bulletin of Marine Science, ISSN 0007-4977, Vol. 88, Nº. 4, 2012, págs. 1061-1074
• Idioma: inglés
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• Resumen

  • The present study examines how the habitat type and food availability influence the small scale distribution and assemblages of opisthobranch species in the National Park Arrecife Alacranes, the largest coral reef system in the southern Gulf of Mexico. Samples were collected during December 2009, and April and September 2010 over different habitats (green, red, and brown algae, seagrass meadows, drifting Sargassum spp., rocks, corals, and sand). In total, 32 species were identified and a multidimensional scaling (MDS) analysis based on the Bray-Curtis similarity index was used to determine the main opisthobranch assemblages. The degree of association between the habitat type and the species composition was tested by a chi-square test and the significance of its value was determined by Monte Carlo randomizations. MDS results defined four faunal associations ("algal", "Thalassia", "Sargassum", and "rocky" assemblages), which showed a significant relationship between the composition of opisthobranch species and the habitat type. These results suggest that food supplies and feeding strategies play a dominant role in the coexistence of species and their small-scale spatial distribution within the reef. The algal assemblage, the group with the highest species richness, was mainly composed of herbivores inhabiting several types of benthic algal communities, whereas the Sargassum assemblage, was a less diversified group comprised of carnivores feeding on epibiont hydroids and was well adapted to the pelagic environment. The distribution of the opisthobranchs over the different habitats largely reflected the variety and availability of their food items.