Impacts of maintenance channel dredging in a northern Adriatic coastal lagoon. I: Effects on sediment properties, contamination and toxicity

Conservation and management of coastal lagoons envisage direct human intervention. To prevent siltation and to preserve the hydrodynamics features of the lagoon system, the inner channels undergo regular maintenance dredging. Sediment properties (RDP, organic matter, grain size), trace metals (Cd, Cu, Cr, Hg, Ni, and Pb), and toxicity vs. the amphipod Corophium insidiosum and the luminescent bacterium Vibrio fischeri, were analysed before and after dredging operations in a coastal lagoon (Pialassa Baiona, Italy). To detect the actual impacts, disturbed sites were contrasted with multiple controls in two distinct times, i.e. before and after the disturbance, according to a sampling design based on Beyond BACI principles. The integrated methodology here adopted suggests that dredging operations carried out are not likely to pose dramatic effects on environmental quality of the lagoon.