Benthic litter in the continental slope of the Gulf of Naples (central-western Mediterranean Sea) hosts limited fouling communities but facilitates molluscan spawning

Seafloor pollution by benthic litter is an emerging phenomenon, although debris colonization by biota remains largely unexplored. We characterized the litter of the continental slope (similar to 400-600 m) of the Gulf of Naples (Mediterranean) and investigated its fouling biota through integrative taxonomic approaches. Plastic pieces (82 %) with land-based origin (96 %) and limited sizes (10-20 cm) were the items most commonly encountered, suggesting a transfer to deep waters through floating and sinking. The majority of the items were not fouled, and the debris hosted an impoverished biota, leading to hypothesize that benthic litter supports wide communities only in shallow waters. Higher colonization rates were observed for gastropod and cephalopod eggs with no preference for materials and sizes, suggesting that even small pieces of soft plastic provide a spawning habitat for molluscs and affect species' connectivity in the deep-sea ecosystem. Holistic approaches are necessary to evaluate interactions between litter and biota.

Automated summary

Seafloor pollution by benthic litter is a growing concern, and the colonization of debris by biota has been understudied. This study found that plastic pieces of land-based origin were the most common items encountered on the continental slope of the Gulf of Naples. The majority of these items were unfouled and supported an impoverished biota. However, gastropod and cephalopod eggs showed higher colonization rates on the debris, suggesting that even small pieces of soft plastic can provide spawning habitat and affect species connectivity in the deep-sea ecosystem.