Temporal evolution of oxygen and nutrients in the NE Ionian Sea from 1987 to 2008 under the influence of the Cretan and Adriatic Seas

Abstract

The Eastern Mediterranean Transient (EMT) was a major climatic event, as it affected profoundly and for a long time period, the circulation of the deep and intermediate layers, with important consequences on the distribution of oxygen and nutrients in the Ionian Sea and more generally, in the whole Eastern Mediterranean basin.In this paper, nutrient and oxygen data collected by the Hellenic Centre for Marine Research, in the Northeastern Ionian Sea, the Western Cretan Sea and the western straits of the Cretan Arc, during the period 1987–2008, were used in order to reveal the detailed pattern of oxygen and nutrient distribution in the NE Ionian Sea, their temporal and spatial variability and their relevance to the two competing sources of deep water, namely the Adriatic and the Cretan Seas.The distributions of oxygen and nutrients before, during and after the EMT are presented and discussed in relation to the physical processes, the circulation and the dynamics of the area. In the post-EMT period there is evidence that deep waters of Adriatic origin are again present in the abyssal depths of the Ionian Sea. However, the oxygen and nutrients concentrations as well as the thermohaline properties in the study area are still far from those observed in the pre-EMT phase.