DEEP-WATER MYSIDS OF THE CATALAN SEA - SPECIES COMPOSITION, BATHYMETRIC AND NEAR-BOTTOM DISTRIBUTION

Deep-water suprabenthic species of Mysidacea were studied in the Catalan Sea (western Mediterranean). Twenty-one samples were taken at depths from 385 to 1859 m, using a Macer-Giroq type sledge. Sixteen mysid species have been collected. Boreomysis arctica was the commonest species and Parapseudomma calloplura, Paramblyops rostrata and Erythrops neapolitana were also notable for their high occurrence. The genus Dactylamblyops, Mysidella biscayensis and Pseudomma affine were recorded for the first time in the Mediterranean. The greatest total abundance of mysids was found over the middle slope. On the upper slope P. calloplura and E. neapolitana formed the dominant species, and deeper B. arctica dominated. Species richness and diversity (H') declined with increasing depth. The decrease in H' was attributable to the growing dominance of B. arctica over the middle and lower slopes. Swimming coefficients near the bottom showed intraspecific differences. In general, the species collected inhabit the water column between 0.1 and 0.5 m above the bottom. The bathypelagic species Eucopia hanseni had high swimming coefficients. Amongst the suprabenthic species, B. arctica showed the highest swimming coefficients, and rose from the near-bottom during night on the upper and middle slope stations.