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In recent highly variable climate, a combined effect of a large-scale northern hemisphere climate and regional-scale Adriatic hydroclimate changes significantly reflected in the Adriatic Sea ecosystem. To clarify this statement we set up in connection two inter-annual systems: the air-sea interconnected system and pelagic ecosystems for the period 1961 to 2010. Within this period, significant changes occurred through 1987-1998 period, characterized by a drop of temperature, salinity and oxygen concentration in the middle Adriatic intermediate layer as consequence of a weaker ventilation of the Adriatic Sea. The pelagic ecosystem reacted to these changes. Large fluctuations in marine biota (from plankton to pelagic fish) revealed significantly different regimes before and after the late eighties. Different patterns observed through analyzed biotic parameters seem linked to modification in thermohaline circulation related to the Eastern Mediterranean Transient (EMT), whose effects prevented warmer and saltier water mass intrusions into the Adriatic Sea. These results provide evidence on connections between the shifts in the middle Adriatic pelagic ecosystem and the northern hemisphere climate via changes in regional atmospheric conditions, and highlight the importance of northern hemisphere climate changes for physical and biological regimes of the Adriatic Sea. [ABSTRACT FROM AUTHOR]

This paper aims to document salinity and temperature regimes in the middle and south Adriatic Sea by applying the Self-Organizing Maps (SOM) method to the available long-term temperature and salinity series. The data were collected on a seasonal basis between 1963 and 2011 in two dense water collecting depressions, Jabuka Pit and Southern Adriatic Pit, and over the Palagruža Sill. Seasonality was removed prior to the analyses. Salinity regimes have been found to oscillate rapidly between low-salinity and high-salinity SOM solutions, ascribed to the advection of Western and Eastern Mediterranean waters, respectively. Transient salinity regimes normally lasted less than a season, while temperature transient regimes lasted longer. Salinity regimes prolonged their duration after the major basin-wide event, the Eastern Mediterranean Transient, in the early 1990s. A qualitative relationship between high-salinity regimes and dense water formation and dynamics has been documented. The SOM-based analyses have a large capacity for classifying the oscillating ocean regimes in a basin, which, in the case of the Adriatic Sea, beside climate forcing, is an important driver of biogeochemical changes that impacts trophic relations, appearance and abundance of alien organisms, and fisheries, etc. [ABSTRACT FROM AUTHOR]