Hydrothermal Vents in Panarea, Italy: Investigating Mercury inputs and evaluating Biota Oxidative Stress Status with a focus on Phorcus turbinatus as a Bioindicator of Mediterranean Sea Health

Panarea, an island in the Tyrrhenian Sea, Mediterranean Sea, is distinguished for its hydrothermal vent ecosystems that substantially influence the local biodiversity. While hydrothermal vents are recognised for their mineral-rich composition, the potential release of mercury (Hg), a non-essential metal, into the surrounding environment raises environmental concerns. This study investigates the oxidative stress status and cellular energy allocation of the autochthonous marine gastropod Phorcus turbinatus (Born, 1778), collected from rocky shores at two distinct hydrothermal vents, Bottaro and La Calcara, characterized by different hydrothermal vent activities. Our results show a higher THg input at La Calcara vent (864 pM) when compared to Bottaro (45.9 pM), suggesting exposure by diet. Accordingly, significantly higher levels of oxidative damage, measured as lipid peroxidation (LPO), were observed in gastropods from La Calcara compared to their counterparts from Bottaro. This observation aligns with lower catalase (CAT) activity and total glutathione levels (tGSH) in these gastropods, indicating compromised antioxidant defenses against reactive oxygen species (ROS). No significant differences were observed in energy metabolism when comparing cellular energy allocation (CEA) between snails from the two locations. Nevertheless, gastropods from La Calcara exhibited significantly reduced levels of available sugars, suggesting potential energetic costs of dealing with higher levels of oxidative stress due to increased Hg exposure. Understanding the complex relationships among hydrothermal vent activity, Hg inputs, Hg transfer in food webs, and biota responses provides valuable insights for conservation and management efforts in these unique and fragile ecosystems. Future research should focus on elucidating the long-term effects of Hg exposure at several hydrothermal vent locations, their biodiversity, and ecosystem dynamics, contributing to the broader understanding of metal contamination in marine environments.