Global Distribution, Composition and Abundance of Marine Litter

Anthropogenic debris on the ocean surface and beaches has significantly increased over recent decades. Initially described in the marine environment in the 1960s, marine debris is nowadays commonly observed across all oceans. Together with their breakdown products, micro-particles, they have become more numerous and can be transported over very long distances  (Barnes et al., 2009). 
Humans generate considerable amounts of waste and the quantities are increasing, although quantities of waste vary between countries. Plastic, the main component of litter, has become ubiquitous and forms sometimes up to 95% of the waste that accumulates on shorelines, ocean surface or seafloor.
 Plastic bags, fishing equipment, food and beverage packaging are the most common items and contribute more than 80% of litter stranded on beaches (Topcu et al., 2012; Thiel et al., 2013). A large part of these materials do not decompose or decompose slowly. This phenomenon can also been observed on the seafloor with benthic trawls contain litter up to 90 % of plastic. (Galil et al. 1995, Galgani et al., 1995 & 2000; ramirez et al., 2013). In some areas on the sea surface the majority of floating litter consists out of plastic.
 Even without   standardized approaches, the abundance and distribution of anthropogenic debris show considerable spatial variability. Strandline surveys, cleaning and regular field surveys are now starting to be organized in many countries in order to provide information about temporal and spatial trends. Accumulation rates vary widely with many factors such as the presence of large cities, shore use, hydrodynamics and maritime activities, at lower rates in the Southern Hemisphere. Enclosed seas such as the Mediterranean or Black Sea may have some of the highest densities of marine litter stranded on the seafloor, reaching more than 100000 /km2. In surface waters, the problem of plastic fragments has become an increased problem in the last few decades. From the first reports in 1972 (Wong et al., 1974), the quantities of microparticles in European seas have increased in comparison to data from 2000 (Thompson et al., 2004) Recent data suggests that quantities of microparticles appear to have stabilized in the oceans over the last decade (law et al., 2010). Little is known about trends in accumulation of debris in the deep sea, as studies are not common. Debris densities on the deep seafloor decreased in some areas, such as the Bay of Tokyo from 1996 to 2003   and the gulf of Lion between 1994 and 2009 (Kanehiro et al., 1995; Kuriyama et al., 2003, Galgani et al., 2011). In contrast, in some areas around Greece, the abundance of debris at depth has increased over a period of 8 years (Stefatos et al., 1999; Koutsodendris et al., 2008). Interpretation of temporal trends is complicated by seasonal changes in flow rate of rivers, currents, swell, winds etc. Decreasing trends of macro-plastics on beaches of remote islands suggest that regulations to reduce dumping at sea have been successful to some extent (Eriksson et al., 2013). However, both the demand and the production of plastics will drastically increase to reach 260 millions tons in 2013.JRC.H.1-Water Resource