Latitudinal gradient of the Patagonian scallop (Zygochlamys patagonica) assemblage.

BREMEC C.; SCHEJTER L.

Mooloolaba, Australia

Workshop; 15th. International Pectinid Workshop; 2003

The aim of this contribution is to give new information about the community structure in northern areas (between 36º-39ºS) and to identify latitudinal variations in the composition of the benthic macroinvertebrates assemblage associated with the Patagonian scallop in order to determine useful parameters to support management recommendations. This study shows that the invertebrates assemblage in Reclutas and MDQ beds is conformed by the faunistic taxa that also characterize the community in southern beds, mainly subantarctic species. Higher species richness, bycatch biomass values (0,067 and 0,057 kg/m2 ) and proportion of echinoderms were found. The northern study areas were characterized by the conspicuous presence of the polychaete Chaetopterus variopedatus, with total bycatch biomass values ranging between 0,022 and 0,035 kg/m2.             The relative presence (% wet weight) of scallop shells and invertebrate rests was lower in northern areas than in Reclutas and MDQ beds.             Our results indicate latitudinal differences in the benthic community structure between septentrional areas of distribution of the Patagonian scallop and Reclutas and MDQ beds, both representatives of the previously described species assemblage. Higher species richness, bycatch biomass values (0,067 and 0,057 kg/m2 ) and proportion of echinoderms were found. The northern study areas were characterized by the conspicuous presence of the polychaete Chaetopterus variopedatus, with total bycatch biomass values ranging between 0,022 and 0,035 kg/m2.             The relative presence (% wet weight) of scallop shells and invertebrate rests was lower in northern areas than in Reclutas and MDQ beds.             Our results indicate latitudinal differences in the benthic community structure between septentrional areas of distribution of the Patagonian scallop and Reclutas and MDQ beds, both representatives of the previously described species assemblage.