Assessment of Fish-Farms Wastewaters Synergistic Impact on a Mediterranean Non-Tidal Lagoon

The impact of wastewater from two fish farms affecting a coastal lagoon has been assessed for water quality, sediments and macroalgae. Based on a previous study, three sampling areas of 135 hectares each were identified at increasing distance from the discharges and six monitoring surveys were carried out between May 2017 and November 2018. The results indicated macroalgal assemblages as the most suitable variables for assessing the impact of wastewater, since they showed a different species dominance in the three areas. No clear result emerged from sediments parameters due to the texture variability, while water quality was significantly different only for nitrates and orthophosphates in one of the three areas. Probably due to the specific lagoon morphology and eutrophication management methods adopted, only one of the surveyed areas was clearly affected by the wastewater impact.