LONG-TERM EUTROPHICATION EFFECTS ON MACROFAUNAL COMMUNITIES IN NORTHERN ADRIATIC SEA

The macrozoobenthic community in the northern Adriatic Sea, south of the Po river, along the Emilia-Romagna region coast, was sampled in 1985. Sampling site was central to a highly eutrophicated area with greatly increased intensity and frequency of dystrophic events over recent decades. The sampled community differs from all those described in the same area in a period (1934-1936) previous to the actual degree of eutrophication. Large abundances of species indicative of unstable bottoms, such as the bivalve Corbula gibba and the polychaete Lumbrineris latreilli were recorded. Moreover, the community structural features indicate a state of immaturity, such as in early successional stage communities. The increased frequency of acute dystrophic events and consequent shortening of the time between successive disturbances is proposed as the cause of biocenosis modification and its current structure and composition.