Temporal Physical and Chemical Bottom Water Changes in the Middle Adriatic Depressions

A physical and chemical dataset collected in the Jabuka (Pomo) depression area (Middle Adriatic Sea) was analysed for seasonal and interannual changes in temperature, salinity, density, dissolved oxygen and nitrates. The historical dataset collected from 1980 to 1997 has been enriched with 30 oceanographic cruises carried out between 1998 and 2008 in the framework of the SINAPSI research program. The bottom water masses of the Jabuka pits are periodically renewed by Northern Adriatic Deep Water (NAdDW) at 1- to 3-year intervals. During late winter-early spring, the new water eventually flows into the western pit and then into the central and the eastern ones. During 1 year of residence in the pits, the bottom water nitrates increase 3-fold and dissolved oxygen decreases by 28% due to mineralisation processes. Some aspects of recently observed decadal climatic anomalies in the Northern Adriatic Sea, in particular the average winter sea surface warming, are revealed by the analysed dataset. Connections may be established with the Eastern Mediterranean Transient (EMT), and indications that after 1999 the Adriatic Sea is returning to be a major producer of the Eastern Mediterranean Deep Water can be inferred. These facts confirms the value of the mesoadriatic depressions as an easily accessible recording site for the interannual oceanographic variations of the Adriatic basin