Climate-plankton interactions across semi-enclosed European Shelf Seas

European shelf seas have undergone significant modifications, including ecosystem-wide shifts from cold-adapted to warm adapted communities. Empirical evidence has been found suggesting that the linkage between winter regional hydroclimate in European shelf seas (North, Baltic, western Mediterranean and central Adriatic) over the period 1950 to 2000 with the North Atlantic Oscillation (NAO) is discontinuous likely as consequence of the long term variations of phase and intensity of the NAO. The long term variations and wavelet power spectrum (not shown) of hydroclimate conditions in the northern seas (i.e. North and Baltic Seas), as well as in southern ones (western Mediterranean and central Adriatic, showed synchronous changes suggesting coherent variations at regional scales in the two areas. In addition, the quantitative synthesis of original investigations on climate effects on Europeanshelf seas shows a clear signature of the NAO on abundance/biomass changes in plankton communities, either phytoplankton or zooplankton, although the strength of the signal on the latitudinal gradient with the southern areas (i.e. western Mediterranean) further linked to subtropical climate variations. Owing to the key role plankton play in marine ecosystems (i.e. target food for small pelagic fish, e.g. anchovy, sprat) this work provides insights into the role of hemisphere-wide climatic processes on the ecological functioning of regional food webs.