Abstract

Marine benthic invertebrates species diversity is analyzed. Samples were obtained using a McIntyre dredge (quantitative sampling), deployed during six periods in a sublitoral zone of the Strait of Magellan, between its First and Second Narrow. Three hundred and one species and major taxonomic categories were identified. Polychaeta, Crustacea and Gastropoda were the dominant groups in terms of species richness. Astarte longirostris, Eurhomalea exalbida and Cyamiocardium denticulatum (bivalves), Trochita pileolus (gastropod), Themiste sp. (sipunculid), Hemipodus simplex and Notocirrus lorum (polychaetes), Magellania venosa (brachiopod) and Euvallentinia darwini (isopod) were the numerical dominant species. All these species have a geographical distribution apparently restricted to the tip of Southern South America, with a distribution in both the Atlantic and Pacific Ocean. The species have not been reported south of the 55°S and north of the 46°S. Univariate parameters used to analyze the biodiversity of sampling sites, indicate an intermediate evenness (J) from few species, with high values of Shanonn-Wiener diversity. Indices show a clear fluctuation trend through time, with a preliminary biodiversity pattern conformed by three value groups. The results suggest the necessity to obtain quantitative values of diversity not only considering spatial references (e.g., area considered for estimations), but also a temporal scale to define range of probable values of diversity (e.g. different sampling periods).