Composition and spatial distribution of cephalopods in two north-western Mediterranean areas

Abstract

The faunistic composition and the spatial distribution of the cephalopod fauna were studied and compared in two areas of the north-western Mediterranean: the Catalan Sea (Spanish coast) and the northern Tyrrhenian Sea (Italian coast). In all, 46 species were collected in the Catalan Sea and 36 in the northern Tyrrhenian Sea. The bathymetric distribution of common species does not differ notably between the two areas. In both, cephalopod abundance is greatest between 50 and 200 m deep. To compare the seasonal changes in bathymetric distribution, four representative species were selected. O. vulgaris is more abundant in both areas between 0 and 50 m in autumn; E. cirrhosa and I. coindetii between 50 and 200 m. Both the last species and S. elegans are more abundant in spring in the Catalan Sea and in autumn in the northern Tyrrhenian Sea. The results of cluster analysis show the presence, in both areas, of three clear associations: one group consists of shallow hauls, another of hauls made over the continental shelf and the third of deeper hauls.