Eva Ramirez-Llodra, Ben De Mol, Joan B. Company, Marta Coll, Francesc 
Sardà, Effects of natural and anthropogenic processes in the 
distribution of marine litter in the deep Mediterranean Sea, Progress in 
Oceanography, Volume 118, November 2013, Pages 273-287, ISSN 0079-6611, 
http://dx.doi.org/10.1016/j.pocean.2013.07.027.
(http://www.sciencedirect.com/science/article/pii/S0079661113001407)
Abstract: The distribution, type and quantity of marine litter 
accumulated on the bathyal and abyssal Mediterranean seafloor has been 
studied in the framework of the Spanish national projects PROMETEO and 
DOS MARES and the ESF-EuroDEEP project BIOFUN. Litter was collected with 
an otter trawl and Agassiz trawl while sampling for megafauna on the 
Blanes canyon and adjacent slope (Catalan margin, north-western 
Mediterranean) between 900 and 2700 m depth, and on the western, central 
and eastern Mediterranean basins at 1200, 2000 and 3000 m depth. All 
litter was sorted into 8 categories (hard plastic, soft plastic, glass, 
metal, clinker, fabric, longlines and fishing nets) and weighed. The 
distribution of litter was analysed in relation to depth, geographic 
area and natural (bathymetry, currents and rivers) and anthropogenic 
(population density and shipping routes) processes. The most abundant 
litter types were plastic, glass, metal and clinker. Lost or discarded 
fishing gear was also commonly found. On the Catalan margin, although 
the data indicated an accumulation of litter with increasing depth, mean 
weight was not significantly different between depths or between the 
open slope and the canyon. We propose that litter accumulated in the 
canyon, with high proportions of plastics, has predominantly a coastal 
origin, while litter collected on the open slope, dominated by heavy 
litter, is mostly ship-originated, especially at sites under major 
shipping routes. Along the trans-Mediterranean transect, although a 
higher amount of litter seemed to be found on the Western Mediterranean, 
differences of mean weight were not significant between the 3 geographic 
areas and the 3 depths. Here, the shallower sites, also closer to the 
coast, had a higher proportion of plastics than the deeper sites, which 
had a higher proportion of heavy litter and were often affected by 
shipping routes. The weight of litter was also compared to biomass of 
megafauna from the same samples. On the Blanes slope, the biomass of 
megafauna was significantly higher than the weight of litter between 900 
and 2000 m depth and no significant differences were found at 2250 and 
2700 m depth. Along the trans-Mediterranean transect, no significant 
differences were found between biomass and litter weight at all sites 
except in two sites: the Central Mediterranean at 1200 m depth, where 
biomass was higher than litter weight, and the Eastern Mediterranean at 
1200 m depth, where litter weight was higher than biomass. The results 
are discussed in the framework of knowledge on marine litter 
accumulation, its potential impact on the habitat and fauna and the 
legislation addressing these issues.