Marine biotopes as management units in the San Jorge gulf, Argentina

ZAIXSO HÉCTOR; BORASO ALICIA; VARISCO MARTIN; VINUESA JULIO

Venecia

Conferencia; 50 Estuarine Coastal and Shell Association Conference; 2013

Estuarine Coastal and Shell Association

The San Jorge Gulf is a wide semicircular ocean basin that opens to the Southwestern Atlantic Ocean, and is an area of marked economic importance. In its central area takes place the larger oil loading activities of the Argentine coasts. Moreover, the Gulf is home of sveral relevant fisheries. It is also inhabited by species whose conservation is particularly relevant, like colonies of sea lions and seabirds, as penguins, cormorants, gulls and terns. The classification and characterization of coastal marine biotopes has proved recently an effective tool when planning the use and potential activities on the coast. It provides a reliable reference, based on the structure and functioning of marine communities present.It also allow to understand the mechanisms of change that can potentially affect them, and its consecuences on the ecosystem. This study aims to characterize the main coastal biotopes of the Gulf, by the identification of principal communities, the list of indicator species, density, biomass or coverage per unit area or volume. It also aims to study temporal (seasonal) variations, as well as measures of ecological indices (eg. Species richness and diversity). The characterization also includes the identification of most important physical and chemical variables structuring those communities. These usually involve the determination of changes in water temperature, salinity, pH, dissolved oxygen, chlorophyll and nutrient concentration, PAR light and turbidity, as well as water agitation and substrate change. Eleven main biotopes were registered: intertidal Perumytilus purpuratus beds, intertidal blue mussel (Mytilus edulis platensis) beds, Crab (Cyrtograpsus spp.) communities, sublittoral mussel (Aulacomya atra atra) beds, salt-marshes, Gracilaria gracilis beds, kelp (Macrocystis pyrifera) forests, subtidal soft bottoms of Ensis macha and Buccinanops globulosum, subtidal Ameghinomya antiqua beds, intertidal Darina solenoides communities, and circalittoral soft bottoms. Biotopes described here have similar characteristics to other sites studied in the Magellanic biogeographic province.