A harmonized and coordinated assessment of the abundance and composition of seafloor litter in the Adriatic-Ionian macroregion (Mediterranean Sea)

Abstract Marine litteris a threat to marine lifeand an economic burden for coastal communities, but efforts to address the issue are hampered by the lack of data for many countries. We performed the first harmonized assessment of seafloor litter( trawland visual surveys) in six countries of the Adriatic- Ionianmacroregion. Seafloor littershowed an uneven distribution throughout the area, with large differences in litterdensities and composition among countries and locations. An emerging problem in the area resulted in short-term & single-use objects that represented the largest fraction of litter. Packaging was the economic sectorcontributing most to seafloor litteron the continental shelfand upper slope, while in some areas aquaculture (mussel farming) represented a key activity producing marine litter. In coastal areas and bays (e.g. Boka Kotorska bay, Montenegro), seafloor litterwas mainly related to construction activities and electronic goods, which are a consequence of fly-tipping/ illegal dumping.