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In the late Miocene, a thick and complex sequence of evaporites was deposited in the Mediterranean Sea during an interruption of normal marine sedimentation known as the Messinian Salinity Crisis. Because the related deposits are mostly hidden from scrutiny in the deep basin, correlation between onshore and offshore sediments is difficult, hampering the development of a comprehensive stratigraphic model. Since the various facies correspond to different salinities of the basin waters, it would help to have physics-based understanding of the spatial distribution of salt concentration. Here, we focus on modelling salinity as a function of depth, i.e., on the stratification of the water column. A box model is set up that includes a simple representation of a haline overturning circulation and of mixing. It is forced by Atlantic exchange and evaporative loss and is used to systematically explore the degree of stratification that results under a wide range of combinations of parameter values. The model demonstrates counterintuitive behaviour close to the saturation of halite. For parameter values that may well be realistic for the Messinian, we show that a significantly stratified Mediterranean water column can be established. In this case, Atlantic connectivity is limited but may be closer to modern magnitudes than previously thought. In addition, a slowing of Mediterranean overturning and a larger deep-water formation region (both in comparison to the present day) are required. Under these conditions, we would expect a longer duration of halite deposition than currently considered in the MSC stratigraphic consensus model. [ABSTRACT FROM AUTHOR]

In the Mediterranean, blue whiting, Micromesistius poutassou, constitutes a traditional fisheries resource. Over several decades, blue whiting landings in the Catalan coast (northwestern Mediterranean) have displayed cyclical variations, of c. 6 yrs, slightly decreased to five in the last two decades, as shown through wavelet analysis. These fluctuations have persisted under very different levels of fishing effort. This study evaluates the hypothesis that deep-water formation in the adjacent Gulf of Lions, and the enhanced primary productivity related to it, determines recruitment strength in blue whiting that results ultimately in the observed periodicity of the blue whiting landings. The link between landings and environmental drivers was explored using lagged cross-correlations, with 0- and 1-yr lag. The variables considered included large-scale indices [North Atlantic Oscillation (NAO) and the Atlantic Multi-decadal Oscillation (AMO)], Mediterranean climate indices [MO and Western Mediterranean Oscillation (WeMO)], and variables defining the local environmental conditions in the northwestern Mediterranean (sea-air heat flux, winter air temperature anomaly and Rhône river runoff). Significant correlations were only found between landings (1961-2011) and sea-air heat flux, which is generally taken as an indicator of processes of deep water convection, at 0 and 1-yr lag. These results suggest that the observed fluctuations in blue whiting landings respond to oceanographic processes taking place in the Gulf of Lions. [ABSTRACT FROM AUTHOR]

The Eastern Mediterranean Transient (EMT) was the major climatic event in the circulation and water mass properties of the Mediterranean in the last century. In this paper, we describe the present status of the EMT and its evolution since 1995 using hydrological and tracer data from 1997 to 1999. Few but important changes have been observed in the circulation pattern. The intrusion of the Asia Minor Current (AMC) that carries the saline Surface Levantine Waters into the Aegean has been reduced compared to the picture of late 1980s. This means that one of the mechanisms that increased the salt content of the Aegean during the peak of the EMT is no longer present. The Modified Atlantic Water (MAW) signal that has been weakened in the Levantine Basin during the early stages of the EMT has also been re-enhanced. The Aegean still functions as a source of deep (Cretan Deep Water, CDW) and intermediate waters (Cretan Intermediate Water, CIW) for the Eastern Mediterranean, although with modified characteristics. The most important changes in the thermohaline structure of the Cretan Sea (southern Aegean Sea) are the weakening of the signal of the old Mediterranean mid-depth waters and the modification of the properties of the CDW both leading to a reduced stratification. The outflowing CDW is no longer dense enough to reach the bottom of the adjacent basins, but ventilates layers between 1500 and 2500 m. Only the deep eastern Straits of the Cretan Arc are still active in the discharge of CDW, while at the western Strait (Antikithira), the density of the outflowing water was reduced significantly. The intermediate water CIW formed in the Aegean is characterized as a shallow CFC-12, temperature and salinity maximum layer, and differs much from the “old” CIW formed before the EMT, which was found in the layer below the Levantine Intermediate Water (LIW). The new CIW extends into the Ionian Basin through Antikithira Strait. It has lately been observed to enter the Adriatic, where its high salinity is expected to re-establish deep-water formation in this basin. The spreading of the CDW that had been deposited in the Cretan Passage in the first phase of the EMT has progressed further. The entire bottom layer of the Levantine Basin is now covered by the CDW. In the Ionian, the CDW has reached the Straits of Sicily and Otranto. Similar pathways in the Ionian are followed by the new shallower outflow of the CDW. [Copyright &y& Elsevier]