Echinoderms in San Matías Gulf, Southwestern Atlantic Ocean

Abstract

Echinoderms are often of ecological importance in intertidal and subtidal waters, especially as predators and herbivores but also as prey. Several groups of echinoderms respond in a different way to environmental variables, contributing to some of the biodiversity patterns found along latitudinal gradient. This work listed the echinoderms species of San Matías Gulf surrounding the coast of Río Negro Province and analyzed the current state of knowledge of this group by previous works, collection items of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia,” and from samples taken since 2009 to the present. A total of 35 species of echinoderms corresponding to four classes were recorded. The 34.29 % corresponds to Asteroidea, 31.43 % to Ophiuroidea, 20 % to Echinoidea, and 14.28 % to Holothuroidea. Crinoidea has not been reported for San Matías Gulf. Asteroidea and Ophiuroidea were the most representative groups followed by Echinoidea and Holothuroidea, with only five species in the last class. About 30 % of the country’s species are present in Río Negro Province. This high number of species may be due to the heterogeneity of environments that are possible to find in San Matías Gulf and a transition zone between the Magellanic and Argentine biogeographic provinces that can provide particular physical and climatic characteristics explaining as consequence the faunal composition.