Reconstructing 150 years of eutrophication in the north-western Adriatic Sea (Italy) using dinoflagellate cysts, pollen and spores

Recent trends in the trophic conditions of the north-western Adriatic Sea have been evaluated using organic-walled dinoflagellate cysts (dinocysts), pollen and spores. Palynological analyses performed on a sediment core covering the period AD 1830-1990 have revealed a progressive increase in eutrophication beginning in the 20th century. The first signal of a change seems to occur earlier in the terrestrial ecosystem and later in the marine realm. Pollen data indicate that the source of enhanced nutrient loading to the North Adriatic Sea, which partly resulted from increased wetland reclamation and forest clearance, began at about AD 1910. The clear shift in the relative abundance of the dinocyst Lingulodinium machaerophorum at AD 1930 suggests an increase in eutrophication. Dinocyst assemblages point to stressful conditions from AD 1960, reaching a maximum at about AD 1978. Subsequently eutrophication levels decrease, although dinocyst diversity suggests that the ecosystem has not completely recovered. (C) 2004 Elsevier Ltd. All rights reserved.