Data collected from different platforms in the Cretan Sea during the 2000s decade present evidence of gradually increasing salinity in the intermediate and deep intermediate layers after the middle of the decade. The observed gradual salt transport toward the deeper layers indicates contributions of dense water masses formed in various Aegean Sea subbasins. The accumulation of these saline and dense water masses in the Cretan Sea finally led to outflow from both Cretan Straits, with density greater than typical Levantine/Cretan Intermediate water but not dense enough to penetrate into the deep layers of the Eastern Mediterranean. We name this outflowing water mass as dense Cretan Intermediate Water (dCIW). A retrospective analysis of in situ data and literature references during the last four decades shows that similar events have occurred in the past in two occasions: (a) in the 1970s and (b) during the Eastern Mediterranean Transient (EMT) onset (1987–1991). We argue that these salinity‐driven Aegean outflows are mostly attributed to recurrent changes of the Eastern Mediterranean upper thermohaline circulation that create favorable dense water formation conditions in the Aegean Sea through salinity preconditioning. We identify these phenomena as “EMT‐like” events and argue that in these cases internal thermohaline mechanisms dominate over atmospheric forcing in dense water production. However, intense atmospheric forcing over an already salinity preconditioned basin is indispensable for creating massive deep water outflow from the Cretan Sea, such as the EMT event.

This chapter, based on numerical modeling and field observations, aims at proposing a different mechanism that drives the alternation of the two competitive dense-water sources, the Adriatic and the Aegean, at quasi-regular, almost decadal, time intervals. The proposed mechanism consists of a thermohaline pump that disturbs the eastern Mediterranean Sea (EMed) upper thermohaline cell, which results in the alternation of the Deep Water Formation (DWF) sources. The authors revisit the datasets of the past century and up to 2010, in order to examine the long-term variability of the thermohaline properties in the EMed, the circulation patterns and DWF processes. The chapter investigates the ability of the hydrodynamic model to simulate the observed changes. The relative importance of the involved forcing factors is examined. The combined modeling and observational results show that the long-term variability cannot be exclusively explained by the atmospheric forcing.

Surface sediments collected from deep basins (1018–4087 m depth) of the eastern Mediterranean Sea (Ionian Sea, southern Aegean Sea and northwestern Levantine Sea) were analyzed for aliphatic and polycyclic aromatic hydrocarbons as tracers of natural and anthropogenic inputs. Concentrations of total aliphatic hydrocarbons, n-alkanes and the unresolved complex mixture (UCM) of aliphatic hydrocarbons varied significantly, ranging from 1.34 to 49.2 μg g⁻¹, 145 to 4810 ng g⁻¹ and 0.73 to 36.7 μg g⁻¹, respectively, while concentrations of total polycyclic aromatic hydrocarbons (PAHs) ranged between 11.6 and 223 ng g⁻¹. Molecular profiles of determined hydrocarbons reflect a mixed contribution from both natural and anthropogenic sources in deep-sea sediments of the eastern Mediterranean Sea, i.e., terrestrial plant waxes, degraded petroleum products, unburned fossil fuels and combustion of grass, wood and coal. Hydrocarbon mixtures display significant variability amongst sub-regions, reflecting differences in the relative importance of inputs from various sources and phase associations/transport pathways of individual hydrocarbons that impact on their overall distribution and fate. Hydrocarbon concentrations correlated significantly with the organic carbon content of sediments, indicating that the latter exerts an important control on their transport and ultimate accumulation in deep basins. Additionally, water masses' circulation characteristics also seem to influence the regional features and distribution patterns of hydrocarbons. Our findings highlight the role of deep basins/canyons as repositories of both natural and anthropogenic chemical species.