Suprabenthic assemblages from Catalan beaches : zoological groups

An analysis of the zoological groups captured with suprabenthic sledges at a depth of 1 m (sampled area 50 m 2 ), has been carried out on 13 Catalan beaches (NE of Spain) with varying profile, exposure, and granulometry. A total of 22104 specimens, belonging to 10 different zoological groups, were obtained (mysids, amphipods, cumaceans, isopods, tanaidaceans, decapods, exuviae of cirripeds, copepods, pycnogonids, and teleosts). The great majority were arthropods and crustaceans, 94.2% being peracarids. The mean density was 34 ind.m -2 and the mean concentration of organic matter 2.89% of the AFDW sediments. Mysids, accounting for 59.9%, constitute the most important group in the Catalan suprabenthos at 1 m depth, followed by amphipods (28.7%). The same groups are also dominant at 5 and 10 m depths on the reflective Masnou beach (86.2% mysids and 8.8% amphipods). In view of the data obtained, we conclude that, at a depth of 1m, the observed faunistic differences are related to the degree of exposure, sand size, and dissipative-reflective character of the analyzed beaches. Moreover, beaches near to the rivers (but not next to) are more dense than remote ones. The hydrodynamics is the basic factor controlling distribution, both vertical and horizontal, of the suprabenthic communities on beaches. Finally, the data of this study are compared to those of the Atlantic suprabenthos obtained from other biotopes. The chief conclusion is that density values decrease with depth. Se analizan los grupos zoológicos capturados con trineos suprabentónicos a 1 m de profundidad en 50 m 2 de 13 playas catalanas de distintos tipos de perfil, exposición y granulometría. Se han obtenido 22104 individuos pertenecientes a 10 grupos zoológicos diferentes (Misidáceos, Anfípodos, Cumáceos, Isópodos, Tanaidáceos, Decápodos, mudas de Cirrípedos, Copépodos, Picnogónidos y Teleósteos). El 95.4% son Artrópodos, el 95.05 son Crustáceos y el 94.2% son Peracáridos. La densidad media es de 34 indiv./m -2 y la concentración media de la materia orgánica es del 2.89% del Pssc (oscila entre 1.4 y 6.2). Los Misidáceos, con el 59.9%, constituyen el grupo más importante del suprabentos catalán a 1 m de profundidad, seguido por los Anfípodos, con el 28.7%. Los mismos grupos también dominan en el conjunto de 5 y 10 m de profundidad de la playa reflectiva del Masnou (86.2 % de Misidáceos y 8.8% de Anfípodos). A la vista de los datos obtenidos se concluye que, a 1 m de profundidad, las diferencias fauní