D - F
type: Concept

DRAKE_BIOSEAS
type: Concept
in scheme: projects
definition: Short Title: DRAKE BIOSEAS Project URL: http://www.tierradelfuego.gov.ar/ipy/ciencia2.php Proposal URL: http://classic.ipy.org/development/eoi/proposal-details.php?id=304 The Southern Ocean exerts a strong influence on global climate through the circulation of the Circumpolar Current and the seasonal shift of the sea-ice cover. While currently there are many different ways of assessing the intensity of phenomena associated with Climatic Change (ozone depletion, increase of temperature, CO2 and UV radiation), there is no single tool for measuring the indirect effects of these alterations, most of which are critical to the functioning of ecosystems. In the marine environment, changes in thermal gradients modify the global oceanic circulation pattern, thus bringing unpredictable consequences to the structure of communities, trophic relationships and biogeochemical cycling. The geographic distribution and abundance of plankton stem from a combination of factors that include the interaction between the life cycle of species, oceanic circulation, formation of eddies, the behaviour of frontal systems (e.g., advance and retreat of the sea-ice cover), and the abundance of vertebrate predators (fish, birds and marine mammals). Any alteration, natural and/or anthropogenic (e.g., fisheries), in the intensity of predation leads to a change in the structure of trophic webs, thus affecting biodiversity, concentration of key Antarctic species, nutrient loading and carbon fluxes to the deep-sea, often resulting in the general unbalance of the ecosystem. In order to examine within an integral framework this conjunction of factors, the present project will focus on the seasonality of one of the most peculiar areas of the Southern Ocean: the Drake Passage, a key open-ocean choke point for the Antarctic Circumpolar Current. The pronounced continental constriction between South America and the Antarctic Peninsula causes the northern deflection of the ACC and, jointly with the ENSO cycles…