Visual observations of floating macro litter around Italy (Mediterranean Sea)

Abstract

We report the results of a visual survey of floating natural (NML) and anthropogenic (AML) macro-litter (>2.5 cm) performed in the central part of the Mediterranean Sea during a dual-use campaign onboard the Italian Navy tall ship “Amerigo Vespucci” which circumnavigated the Italian peninsula during May-June 2016. The distribution, abundance and composition of floating marine litter were assessed using a 10 m fixed-width strip transect method. Over 88 h of transect counts were performed, for a total of 168 transects, covering an overall survey length of 1026.35 km. 4756 anthropogenic litter items were counted during the transects, 96.9 % of which were classified as plastic items. Floating litter was found throughout the entire study area with densities ranging from 0 to 9205 items/km2 and with a mean abundance of 492 AML items/km2 and 77 NML items/km2 across all surveyed locations. Maximum AML densities (>3500 items/km2) were recorded in the Adriatic Sea, while the lowest densities (<50 items/km2) were found along the coastline of Sardinia and in the Strait of Messina. Our results document the ubiquitous presence of floating plastic litter around the Italian peninsula and underline the need to expand our knowledge about the main sources, transport, accumulation and fate of marine litter in the entire Mediterranean region.