105 | The invasive crab Callinectes sapidus as a model for assessing sub-lethal effects of polyvinyl alcohol

Alessandra Maganza^1|2, Alice Gabetti¹, Camilla Mossotto^1|2, Alessia Merialdi¹, Monia Renzi³, Francesca Provenza⁴, Serena Anselmi⁴, Antonia Concetta Elia², Giorgia Zicarelli¹, Annalisa Cotugno¹, Giuseppe Esposito¹, Caterina Faggio^5|6, Marino Prearo¹, Paolo Pastorino¹ | ¹The Veterinary Medical Research Institute for Piemonte, Liguria and Valle d’Aosta, Torino, Italy; ²Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy; ³Bioscience Research Center, Orbetello, Italy; ⁴Department of Life Sciences, University of Trieste, Trieste, Italy; ⁵Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy; ⁶Department of Eco-sustainable Marine Biotechnology, Stazione Zoologica Anton Dohrn, Napoli, Italy.

Plastic materials are among the most influential technological innovations of the twentieth century thanks to their low cost, mechanical resistance, versatility, and durability. Water-soluble polymers (WSPs), often referred to as liquid plastics, have attracted increasing attention due to their ability to dissolve or disperse in aquatic environments under specific physicochemical conditions. One of the most extensively produced classes of synthetic WSPs are polyvinyl alcohols (PVAs), which are commonly employed in industrial, medical, pharmaceutical, and personal care applications. Due to their widespread use, PVAs are continuously introduced into aquatic ecosystems, where they are now considered among the most abundant WSPs. Despite their presumed low toxicity, knowledge of the environmental fate and biological effects of PVAs remains limited. Among decapod crustaceans, the blue crab Callinectes sapidus, an euryhaline species invasive in the Mediterranean Sea, combines high environmental tolerance with invasive status, making it a suitable species for laboratory studies while minimizing the impact on native fauna. Crabs were exposed to three PVA concentrations (0.5, 5, and 25 mg L^–1) along with a control group, for periods of 10 and 20 days, and biological responses were evaluated using an integrated approach combining cytotoxicity assays and oxidative stress biomarkers in multiple tissue, including superoxide dismutase (SOD), glutathione S-transferase (GST), glutathione peroxidase (GPx), and lipid peroxidation (LPO). Cell viability analyses showed high resistance of haemolymph cells, with consistently elevated viability across treatments and exposure times. Hepatopancreas cells were more sensitivity, particularly after prolonged exposure, as evidenced by alterations in lysosomal membrane stability. This tissue-specific response is consistent with the central role of the hepatopancreas in metabolic and detoxification processes and suggests the occurrence of sublethal cellular stress. Antioxidant responses displayed clear concentration and time dependent trends. SOD activity increased across tissues, indicating activation of the primary antioxidant defence, while GST and GPx enzymes showed variable modulation, reflecting the engagement of downstream detoxification pathways. Elevated LPO at higher exposure levels provided evidence of oxidative damage to cellular membranes. Integration of biomarker responses through the Threshold-based Integrated Biomarker Response (IBR-T) index further highlighted tissue-specific sensitivity and complex physiological response patterns. The results indicates that PVA is not biologically inert on aquatic organisms, inducing measurable sublethal effects that may compromise organism health over prolonged periods. These findings highlight the need for further research addressing environmentally relevant concentrations, longer exposure scenarios including recovery phases, and the integration of molecular endpoints to improve the ecological risk assessment of WSPs in aquatic ecosystems.