Climate and Pelagic Ecosystems in Semi-Enclosed Marginal Seas: The Case of European Shelf Seas

European shelf seas have undergone significant modifications, including ecosystem - wide shifts, changes in the timing of ecological events and alterations in species interactions. These changes have been identified over a large spectrum of the marine food web, ranging from phytoplankton to fish, and a significant amount of these variations has been linked to modifications in large scale climate patterns which occurred in the second half of the 20th century. In the European shelf seas the vulnerability of marine ecosystems to climate modifications is enhanced by increasing anthropogenic stress, e.g. excessive fishing. This particularly strong human pressure can trigger abrupt changes at the ecosystem level such as the collapse of fish stocks, the favouring of gelatinous plankton outbursts, or cascading effects that indirectly favour harmful algal blooms. Here we explore the response of plankton trophic levels to climate forcing in five European shelf seas: the northwestern Mediterranean, Adriatic Sea, North Sea, Baltic Sea, and Black Sea. Results showed that the relationship between climate and plankton reveals periods of coherent changes in which the two signals vary in synchrony and other periods in which their linkage is uncoupled. Overall, these results emphasize the non - stationary behaviour of the link between climate and plankton.JRC.DDG.H.3-Global environement monitorin