Marine biodiversity in the north of the magellanic province (43 49' - 41 32' S): composition and spatial patterns of diversity of subtidal molluscs

The fjords and inner waters present in the south of Chile constitute an area of great ecological and zoogeographical interest. In the year 2004 a biodiversity research was carried out as part of the CIMAR 10 Fiordos cruise, that allowed the obtaining of subtidal samples of molluscs in the northern end of the Magellanic Province. In this study we present an analysis of the composition, diversity and space distribution of the molluscan fauna obtained in the cruise. A total of 23 sites, distributed between Seno Reloncavi (41 31' S) and Boca del Guafo (43 99' S) were sampled. The samples were obtained using an Agassiz trawl (of 10 mm of mesh; sampling 10 minutes), to depths between 22-353 m. A total of 67 species were recorded, consistent in 4% Polyplacophora, 58% Gastropoda, 36% Bivalvia and 1% Scaphopoda. The results show that the subtidal species have a high proportion of species with southern features, characteristic of the Magellanic Province. The multivariate analyses allowed to recognize six areas inside the studied territory, clearly recognizable for their composition and species richness.Original Abstract: Los fiordos y aguas interiores presentes al sur de Chile constituyen una zona de gran interes ecologico y zoogeografico. En el ano 2004 se realizo un proyecto de investigacion sobre biodiversidad como parte del crucero CIMAR 10 Fiordos, que permitio la obtencion de muestras de moluscos submareales en el extremo norte de la Provincia Magallanica. En el presente estudio, se entrega un analisis de la composicion, diversidad y distribucion espacial de la malacofauna obtenida en el crucero. Se muestreo en 23 estaciones, distribuidas entre el seno Reloncavi (41 31' S) y la boca del Guafo (43 99' S). Las muestras se obtuvieron mediante una rastra Agassiz (abertura de malla de 10 mm; lances de 10 minutos), a profundidades entre 22-353 m. Se registro un total de 67 especies, consistentes en un 4% Polyplacophora, 58% Gastropoda, 36% Bivalvia y 1% Scaphopoda. Los resultados muestran que las especies submareales presentan una elevada proporcion de especies con caracter austral, propios de la Provincia Magallanica. Los analisis multivariados permitieron reconocer seis areas dentro del territorio estudiado, claramente reconocibles por su composicion y riqueza de especies.