Marine litter as a tool to enhance ecological restoration

Marine litter represents an important threat for marine organisms and ecosystems and increasing efforts are dedicated to the removal of this source of impact. At the same time, marine litter is a substrate often colonized by species of conservation interest and therefore represents an overlooked resource for restoration. Here we conducted a literature survey to catalog the species colonizing marine litter. We found that many species, including some of high conservation interest, colonize the marine litter, particularly the abandoned fishing gears. Overall, we documented 41 macro- and megafaunal species, of which 88 % are currently protected by national and international laws or included in the IUCN Red List. The list of species includes either shallow-water and deep-sea corals, deep-sea bivalves, crustaceans, polychaetes and sponges. We propose the use of these species in marine ecosystem restoration along with a protocol to separate them from the litter, transfer them to aquaria, cultivate those most adaptable to captivity, and subsequently transplant them into impacted areas or use them in experimental studies. This approach has the advantage of replacing or minimizing the need to collect new organisms from pristine habitats. Since several organisms colonizing the marine litter belong to deep-sea species, this approach can promote active restoration interventions also in vulnerable deep-sea habitats. We conclude that, while preventing litter pollution is mandatory, marine debris removal can be an opportunity, through collaboration with the fishery sector, to develop a valuable strategy for the expansion of marine ecosystem restoration.