Manipulative experiment to assess the effectiveness of different methods to reduce the hull biofouling in a touristic marina

Biofouling represents the attachment of undesirable molecules, micro and macro marine organisms to submerged structures such as vessels and offshore structures. Its negative effects include increased drag on vessels, mass gains of offshore structures and acceleration of corrosion processes on submerged structures. Moreover, hull biofouling is known to be one of the main vectors of introduction of non-indigenous species (NIS), that pose serious threat to marine biodiversity. NIS are defined as the array of species directly or indirectly introduced by human activities into environments that are outside their natural distribution range. To early detect the biofouling communities and the arrival of NIS, monitoring benthic communities in marinas is essential. Here, for the first time in Marina di Ravenna, North Adriatic, we tested a standardized protocol developed by the Smithsonian Environmental Research Center to evaluate the impact of different management practices on biofouling, particularly by comparing colonization patterns between cleaned and untreated surfaces over a six-month period, from April to October 2024. The protocol uses standardized PVC settlement panels which are deployed in ports and marinas environments to mimic the surfaces of artificial structures such as docks, piers, and boats. The colonizing sessile communities were assessed using percentage coverage of the taxa trough point count method, and the vagile fauna was identified morphologically using a stereomicroscope and light microscope. Overall, 53 taxa were detected, 11 of them were NIS belonging to five different Phyla. All NIS were already observed in port environments in the Mediterranean Sea. The obtained results seem to confirm that the different treatments applied on the panels can change the community composition. Furthermore, it has been shown that the use of settlement panels seems to be a strong and effective tool to control the presence and abundance of fouling species and NIS.