Historically, Lake Orta has been severely impacted by industrial pollution, which led to the disruption of its biological communities. Although remediation measures, mostly liming, have driven significant ecological recovery, the ecosystem has not yet been fully restored and remains vulnerable to potential new sources of both industrial and domestic pollution which remain largely overlooked.

To address these concerns, the INTEGRARE project aims to assess the presence of anthropogenic contaminants and evaluate their biological effects on benthic communities. To achieve this goal, an active biomonitoring was implemented using the native bivalve Unio elongatulus, a species that has recently recolonized the lake. Organisms from a population in Lake Maggiore were translocated and maintained in cages deployed across five sites in the Cusio area characterized by differing gradients of anthropogenic pressure: Imolo, San Maurizio d’Opaglio, Pella, Omegna, and Bagnera.

The caged bivalves were sampled after 2 and 6 months of exposure. Heart rate was monitored alongside a suite of biochemical biomarkers, including: energetic metabolism (electron transport system activity), oxidative stress (reactive oxygen species levels, and SOD, CAT, and GST enzymatic activities), oxidative damage (lipid peroxidation), and neurotoxicity (acetylcholinesterase activity). The same biological endpoints were measured in resident populations of Lake Orta located at Gozzano and Bagnera.

The results revealed distinct biomarker profiles between the Lake Orta and Lake Maggiore populations, reflecting the different baseline environmental conditions of the two lakes. Notably, no significant differences in the analyzed parameters were observed among the five caging sites within the Cusio area, suggesting the absence of active point sources of contamination in Lake Orta. Overall, the successful translocation procedures and the sensitivity of the biological responses validate the suitability of U. elongatulus as a model organism for assessing the ecological quality of lake ecosystems.

Acknowledgments: “This research was funded by Cariplo Foundation Bandi Emblematici Provinciali Novara”.