CADIC   02618
CENTRO AUSTRAL DE INVESTIGACIONES CIENTIFICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Grazing pressure of mesozooplankton under anthropogenic impact in Ushuaia Bay, Argentina
Autor/es:
DIODATO, S. L.; HOFFMEYER, M. S.; BIANCALANA, F.
Lugar:
Berlín, Alemania
Reunión:
Conferencia; International Council for the Exploration of the Sea; 2009
Institución organizadora:
International Council for the Exploration of the Sea
Resumen:
Ushuaia Bay (on the Northern coast of Beagle Channel, Argentina) is under incipient ecological damage due to discharges of pollutants (sewage and industrial effluents, hydrocarbons and urban wastes). As coastal zooplankton tolerates environmental stress and responds quickly to anthropogenic changes, it is an excellent indicator of the ecosystem health. Feeding is therefore a key issue in the study of trophic interactions. The purpose of this work was to assess the grazing impact of mesozooplankton in two regions of Ushuaia Bay with different anthropogenic pressure: polluted Coastal Station (CS) and unpolluted External Station (ES), in austral midsummer. Grazing experiments were performed using mesozooplankton grazers and natural food <100 µm (auto- and heterotrophic microplankton). Individual and community feeding rates were estimated for each food fraction after 24 h incubation using the particle removal method. Preys and grazers were qualitatively and quantitatively analysed, yielding results in abundance and carbon terms. Differences in mesozooplankton composition between both stations were observed. Predominance of copepods such as Oithona similis, Acartia tonsa and Eurytemora americana, and Podon leuckarti was recorded in CS. Nauplii and copepodids of herbivorous calanoids were dominant in ES. The different values obtained from feeding rates demonstrate the importance of the type and amount of food available, and of the concentration and diversity of grazers, and suggest the existence of two trophic subsystems, i.e. one associated to bentho-pelagic coupling maintained by Macrocystis prairies in the coastal zone and another more related to Beagle Channel plankton in cleaner waters of the outskirts of Ushuaia Bay.