Recreational boating in the Mediterranean Sea has shown to be a major vector for the introduction of non-indigenous species (NIS) via biofouling. In order to prevent its development on submerged artificial hard substrates antifouling coatings are commonly applied. Biocidal coatings (BC), typically based on copper and booster biocides, remain the most widely used despite concerns regarding their long-term performance and potential environmental impacts. Alternatively, non-toxic foul-release coatings (FR) are emerging as more sustainable choices. This study investigated how environmental conditions influence metal leaching from antifouling coatings and developed a screening procedure to assess their toxicity using selected marine species relevant to biofouling and biosecurity.

Antifouling lixiviates were prepared by incubating coated PVC panels with standardized surfaces under six controlled temperature and salinity scenarios. Metal release was quantified using inductively coupled plasma mass spectrometry (ICP-MS). Toxicity was assessed in the amphipod Monocorophium insidiosum and pediveliger larvae of the mussel Mytilus galloprovincialis, both common biofouling target species, and the copepod Acartia tonsa as a non-target species. Field data was used to complement the findings.

Results show diverse metal release across incubation scenarios, indicating a context dependent release of metals to the environment. Regarding the toxicological profiles, FR coating lixiviates did not have an effect on the survival of any of the tested species, while BC coating lixiviate lead to mortality at relatively low concentrations for A. tonsa. Higher BC concentrations were needed for the other two tested species, suggesting that the response is species specific and tolerance phenomena across species. These results were further backed up by previous field data. Overall, such findings could have important implications for biofouling management and biosecurity.