TESTING MUSSELS’ EFFICIENCY AS A BIOREMEDIATION TOOL TO MITIGATE HEAVY METAL POLLUTION

Experiments were performed to evaluate freshwater mussels’ potential use as tools to reduce pollution in the frame of Horizon SYMBIOREM Project (ID 101060361) aimed at developing integrated bioremediation solutions capable of removing multiple pollutants at the same time. FMs were chosen for their ability to filter large volumes of water, removing suspended particles (phytoplankton, bacteria, viruses) and contributing to the sequestration and/or transformation of pollutants (e.g., heavy metals, pesticides, microplastics, pharmaceuticals). Since FMs can be effective in promoting plant growth and nutrient absorption within ‘Constructed Wetlands’ (an ecological engineering solution for removing and transforming pollutants from wastewater) SYMBIOREM aims to develop a floating wetland system with symbiotic cultivation of FMs suspended in the submerged rhizosphere to more efficiently biodegrade or accumulate nutrients and pollutants. Estimation of mussels’ bioaccumulation capacity was done by comparing heavy metals concentrations in soft tissues and shells of a common species (Unio elongatulus) with a Southern European distribution range. A very convenient situation for this study was provided by the recent translocation of mussels of this species from Lake Maggiore (with low levels of metal contamination) to Lake Orta (with high metal contamination dating back to the last century), both located in northern Italy. To seize the opportunity of this natural laboratory, metal concentrations were compared between three populations of mussels: the donor population, the one translocated six years ago and the one that spontaneously recolonized around 2000. At the same time, the microbiota of the mussels of the 3 sites was analysed. Here we present the comparison of bioaccumulation in the soft tissues and shells of the mussels of the 3 populations as related to heavy metals levels the sediments of the 3 sampling sites.