Control of macroalgae blooms in the Lagoon of Venice

The present work is part of the program financed by the Italian Government to save Venice and its lagoon. The aim of the program is the identification, design and construction of the interventions needed both to protect the territory from flood events and to improve the quality of the ecosystem. This paper reports on the progress of the work concerning the second point. ive blooms of macroalgae of the type Ulva rigida leading to anoxia in large parts of the Venice lagoon are rapidly reducing the quality of the ecosystem and affecting its use as a natural resource for fishing, acquiculture and recreation. controlled eutrophication of the lagoon is caused mainly by the presence of high loads of nutrients and the particular morphological and hydro-dynamic setting of the lagoon. ying techniques using GIS capabilities were adopted to assess the relative importance of the physical and chemical factors for each part of the lagoon and the most vulnerable areas were identified. malize the cause-effect chains in the Venice lagoon an ecological model was set up based on a fine-grid hydrodynamic flow field. The ecological model focused on the life cycle of the macroalgae. It includes the processes of overwintering, growth and decomposition as well as the horizontal transport due to wind and the circulation induced by the tide. ed use of the GIS and the model has allowed the definition of the most promising strategies based on the present understanding of the functioning of the ecosystem.