Unfolding connectivity patterns along the Antarctic Circumpolar Current in the sub-Antarctic region

The sub-Antarctic region -here considered between the sub-Antarctic Front and the southern boundary of the Antarctic Circumpolar Current (ACC) -falls under many distinct jurisdictions, including Exclusive Economic Zones (EEZs) of several countries, as well as the areas of competence of several international bodies as the SEAFO, SIOFA and CCAMLR. However, in oceanographic terms, these zones appear mostly as a continuum, due to the connecting effectof the ACC. In this paper we review some techniques which have been developed recently in order to trace connectivity and dispersal patterns induced by the horizontal transport. These are satellite-based Lagrangian methods, which predict remarkably well the extent of phytoplanktonic blooms occurring for hundreds of kilometres in the wake of nutrient sources like islands, seamounts, and hydrothermal vents. These quantitative methods can be applied as well to areas under and beyond national jurisdictions. As an example, we show here the cross-boundary dispersal patterns of the water within and beyond the EEZs in the sub-Antarctic. These patterns inform on the incoming and outcoming pathways of tracers transported in the upper layer, like fish larvae and possible pollutants. The high connection of the physical and biological processes and the cross-boundary physical linkage suggests a geographically integrated evaluation of the sub-Antarctic region.