Trophic status changes In the Venice Lagoon in the last 40 years.

In the Venice lagoon nutrient concentrations increased significantly up to the end of the 1990s both in surface sediments and water column. Consequently, abnormal biomasses of thionitrophilic macroalgae colonised the lagoon contributing to their further increase. In the successive years, both macroalgal biomass and nutrient concentrations declined and the ecological status of the lagoon increased. These trophic changes are presented by analysing their variation both in the central lagoon since the 1980 and in the whole lagoon from the early 2000s.