Potential role of plastic waste as an artificial substrate for the settlement of benthic organisms

Plastic pollution has, in recent decades, been recognized as one of the most serious threats to marine ecosystems. By altering habitats, plastic can increase their structural complexity, leading to the formation of a new ecosystem, the "Plastisphere." This recently coined term emphasizes the inevitable and continuous adaptation of many organisms to the presence of plastic in the environment, particularly in the marine environment, where they sometimes exploit it to their advantage. It is within this perspective that the present research was developed, aiming to investigate the potential role of plastic litter as an artificial substrate for the settlement of benthic organisms. The study focuses on the Natural Oriented Reserve of Capo Peloro Lagoon (Messina, Italy) and the Šibenik area (Croatia), both characterized by freshwater inputs. An important aspect of the study is the comparison of an artificial substrate (plastic litter) with a natural substrate (the valves of the pearl oyster Pinctada radiata Leach, 1814), in order to highlight similarities and differences in colonization and exploitation by benthic organisms. For this purpose, a comparative research project was conducted, involving periodic sampling of plastic litter and samples of P. radiata. The collected data were processed to assess the influence of different sampling areas and periods and to compare the benthic communities that colonized the two substrate types. The results of the present research will contribute useful information to better understand the role of plastic litter in marine ecosystems, both in terms of the spread of Non Indigenous Species (NIS) and biodiversity conservation.