Distribution and seasonal variability of nutrients and dissolved-oxygen in the northeastern ionian sea

In this paper we present for the first time detailed nutrient and oxygen figures for the Ionian Sea. The data were collected during cruises in March-April 1987 and August-September 1987, in the framework of the multi-nation research programme for the exploration of the Eastern Mediterranean, POEM. The oxygen and nutrient pattern is affected by the presence of mesoscale cyclonic and anticyclonic gyres in the area, the most interesting feature of which is the large anticyclonic flow region southwest of Peloponnesus (Pelops gyre). The chemical characteristics of the main water masses were also determined. In the deep layer of the stations near the Otranto Strait we have found, in winter, newly formed Adriatic Bottom Water (O2 : 5.3 ml/l). This water mass has a clear evolution between winter and summer, whereas the Deep Water of the Eastern Mediterranean shows a very small seasonal variation in oxygen and nutrients. The Levantine Intermediate Water is slightly poorer in nutrients and richer in oxygen in summer. A study of the spatial evolution of water masses is also presented.