Spatial and temporal distribution of marine litter on the seafloor of the Balearic Islands (western Mediterranean Sea)

Marine litter, and more specifically the plastic fraction, have been studied in the seafloor around the Balearic Islands. A total of 806 scientific bottom trawl hauls from 15 years of surveys (2001–2015) were analyzed covering a depth range from 38 to 800 m. Marine litter was detected in 88% of the hauls sampled, with a mean value of 1.39 ± 0.13 kg/km². For the plastic fraction, the mean value obtained was 2.73 ± 0.26 kg/km², with its presence in 66% of the sampled hauls. Amongst a series of analyzed factors, that may explain the distribution of seafloor plastics in the study area, sampling area, bathymetric strata and distance to the coastline were identified as significant. High quantities of seafloor plastics were observed along the northwestern coast of Mallorca, which could be related to oceanographic features, and in the continental shelf, close to the coastline, as well as in the upper slope. However, no increasing or decreasing temporal trend in abundance of seafloor plastics was seen throughout the 15 years of scientific surveys