Epibenthic assemblage associated with scallop (Zygochlamys patagonica) beds in the argentinian shelf

Abstract

By-catch samples were taken in patagonian scallop (Zygochlamys patagonica King and Broderip, 1832) beds during a survey evaluation on the Argentinian continental shelf between 38º-46º S in 1995, prior to the development of the present commercial fishery. The invertebrate epibenthic fauna was identified and the community structure was analyzed using univariate and multivariate methods. Patagonian scallop was dominant in weight. In four geographical areas a characteristic assemblage of associated species (sponge Tedania sp., anemone Actinostola crassicornis, echinoderns Ophiactis asperula, Ophiacanta vivipara, Ophiuroglypa lymani, Sterechinus agassizii, Austrocidaris canaliculata, Cosmasterias lurida, Ctenodiscus australis, Psolus patagonicus and Pseudocnus dubiosus leoninus) could be defined by cluster analysis. Areas differed in biomass of scallops and by-catch and also in the relative presence of scallop epibionts. This study gives baseline information on the undisturbed condition of natural communities and will permit future evaluation of structural changes due to fishery impact, since commercial fishing has taken place on the beds since 1996.