Stable oxygen isotope composition of planktonic foraminifera from the Adriatic Sea

Under modern conditions, the reoxygenation of eastern Mediterranean deep water is the result of the formation of dense bottom water in the southern Adriatic Sea. Oxygen isotopic records of planktonic foraminfera used as a paleosalinity tracer show that Po River and/or the alpine glaciers meltwater are not directly responsible of the inhibition of the deep water formation in the Adriatic, during sapropel (S1) formation at 9,000 years B.P.. Sedimentological evidence indicates that fully oxygenated conditions in the deep Adriatic occurred only by 1,650 +/- 100 years B.P., a long time after the total reoxygenation of the deep eastern Mediterranean. Organic carbon content and isotopic ratio indicate that persistence of a reduced sediment phase until 1,650 years B.P., does not result from increased primary productivity or large input of terrestrial organic matter.