Compliance of the macrophyte quality index (MaQI) with the WFD (2000/60/EC) and ecological status assessment in transitional areas: The Venice lagoon as study case

The analysis of the macrophyte assemblages and several environmental parameters measuring anthropogenic pressures indicate that the worst ecological status mainly depends on the combination of high sediment re-suspension, water turbidity and nutrient availability. High water turbidity and the settlement of fine particles prevent the macrophyte attachment to the bottom and their growth also in the presence of nutrients. Under those conditions macrophytes are almost missing and opportunistic taxa, belonging to Gracilariaceae, Solieriaceae and Vaucheria submarina, are replacing Ulvaceae.