Space-time variation of Scleractinia, Gorgonacea, Gastropoda, Bivalvia, Cephalopoda, Asteroidea, Echinoidea and Holothuroidea, from shallow bottom in San Jose Island, Gulf of California

Between the years 1999 and 2000, six expeditions were made to Isla San José, in the Gulf of California. Observations and samples were taken of benthic macroinvertebrates in nine locations. Based on the samples, the specific components of three phyla were determined: Cnidaria (Scleractinia and Gorgonacea), Mollusca (Gastropoda, Bivalvia and Cephalopoda), and Echinodermata (Echinoidea and Holothuroidea). The abundance of conspicuous benthic macroinvertebrates was visually estimated through free dives at a depth of between two and six meters along two transects parallel to the coast. A total of 38 taxa in three groups were determined. The most abundant species are Tripneustes depressus (44,9%), Echinometra vanbruntii (18,3%), Phataria unifascialis (8,9%), Centrostephanus coronatus (8,0%), Diadema mexicanum (5%) y Eucidaris thouarsii (3,6%). No significant differences between diversity (H'), equity (J) and richness of the species (S) during the months and site of study. The similarity analysis identified two groups from locations of the eastern and western coasts.