Macrozoobenthic fauna associated with benthic marine litter (Northern Tyrrhenian Sea, Italy) and first report of two bryozoan species in Italian waters

Abstract

Marine litter is a serious global environmental threat that has received increasing attention in the last decades from the academic world, intergovernmental organizations and agencies due to its impact on ecosystems, fisheries and, ultimately, human health. The Mediterranean Sea is characterized by one of the highest densities of marine litter in the world: although much research has been conducted on floating litter, little data exist on benthic litter and its associated macrozoobenthic fauna and only one study has investigated the matter in Italian waters. In the present work, marine litter was collected through demersal trawl nets in the coastal sector of Civitavecchia (northern Tyrrhenian sea, GSA 9) at 50–120 m of depth with the aim of (i) describing the marine litter-associated macrozoobenthic community, (ii) identifying the associations between macrozoobenthic species and litter categories and (iii) evaluating the presence of unrecorded and/or non-indigenous species (NIS) associated with marine litter. Marine litter was recovered from all hauls, confirming its ubiquity and global dispersion in coastal areas, with plastic materials being the most frequently retrieved category. The highest and lowest litter items density were 2125 and 312.50 items/km2. A total of 656 litter items weighing 15.8 kg were classified according to the MSFD Technical Group on Marine Litter categories and analyzed. Their associated fauna consisted of 1536 benthic organisms belonging to 62 species. Species abundance-wise, Bryozoans were the dominant taxon followed by Polychaeta, Bivalvia, Ascidiacea and Anthozoa. Six non-indigenous species (NIS) were retrieved on anthropogenic substrates and, among them, two bryozoans species previously unreported in Italian waters were herein recorded. At last, our results highlight the possible selective association between some sessile species and specific marine litter categories, even though further validation is needed.