“Marine litter is defined as any persistent, manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment” (UNEP 2009). It is a global problem, with marine litter floating in the water, washed ashore on beaches and even found in deep remote areas (Pham et al. 2014).
Plastics have been recognized as the most abundant and persistent form of marine litter globally. The most comprehensive study to date suggests that 4.8-12.7 million metric tonnes of plastic waste enters the oceans annually, which is equivalent to 1.7-4.4% of the total plastic waste generated by coastal countries (Jambeck et al. 2015). It is estimated that over 5 trillion plastic pieces are currently floating around the world’s oceans (Eriksen et al. 2014). The chemical and physical properties of plastics, which make plastic materials versatile and useful in our everyday life, also make plastics a priority for marine litter management. The manufacturing process of plastic items requires the addition of often toxic additives to give plastics certain properties, whereas the hydrophobic nature of plastics means that they attract persistent organic pollutants found in the water (Andrady 2011; Deanin 1975; Koch et al. 2009; Rochman et al. 2013a; Tanaka et al. 2013). Cigarette butts, made of cellulose acetate, a form of plastic, also contribute to the accumulation and release of pollutants in the marine environment, as they have been found to be a point source of metal contamination, which can lead to the risk of acute harm to marine organisms (Moerman and Potts 2011).
Large pieces of plastic, called macroplastics, do not biodegrade but rather break down into continuously smaller pieces forming what is known as microplastics – plastic items smaller than 5 mm (Thompson et al. 2004; Arthur et al. 2009).
Encounters between marine litter and 693 species of marine organisms have been reported in literature, nearly 90% of which involve plastic litter (Gall and Thompson 2015). Such encounters have detrimental impacts on marine organisms. Macroplastics, such as plastic bags, six-pack rings and fishing-related items can be ingested by larger marine organisms causing blockages of the intestinal tract leading to starvation, and reduced fitness (Bjorndal et al. 1994; Ryan 1988; Spear et al. 1995). Marine organisms can also become entangled in these items, causing incapacitation, reduced preying/feeding abilities, lacerations, suffocation and drowning (Derraik 2002; Gregory 2009; Laist 1997). Microplastics can be ingested by marine wildlife transferring organic pollutants to their bodies, which can cause various health impacts, such as reduced energy reserves (Rochman et al. 2013b; Wright et al. 2013). Recent studies have shown that this can have important impacts on the food chain, as ingested microplastics have been identified in marine organisms destined for human consumption (Browne et al. 2008; Van Cauwenberghe and Janssen 2014). The possible effect that this can have on human health remains uncertain.
Over the years, several studies have investigated the amount and distribution of marine litter, and specifically plastics, in Europe and the Mediterranean (e.g. Aliani et al. 2003; Alomar et al. 2016; Baztan et al. 2014; Collignon et al. 2014; Eryaşar et al. 2014). Most recent estimates suggest that there are approximately 1455 tonnes of floating plastic in the Mediterranean, with microplastics - most with surface area of 1 mm2 - being ubiquitous (Ruiz-Orejón et al. 2016). An investigation of microplastic ingestion in the fish Boops boops in the Mediterranean has found that 68% of examined stomach samples from this species in the Balearic Islands had microplastics in them, at an average of 3.75 items/fish (Nadal et al. 2014), highlighting that Mediterranean marine biodiversity is under threat from the increasing presence of plastics (Deudero and Alomar 2015).
Information taken from: Loizidou, Loizides & Orthodoxou, (2018). Persistent marine litter: small plastics and cigarette butts remain on beaches after organized beach cleanups, Environ Monit Assess, 190:414, https://doi.org/10.1007/s10661-018-6798-9
Plastics have been recognized as the most abundant and persistent form of marine litter globally. The most comprehensive study to date suggests that 4.8-12.7 million metric tonnes of plastic waste enters the oceans annually, which is equivalent to 1.7-4.4% of the total plastic waste generated by coastal countries (Jambeck et al. 2015). It is estimated that over 5 trillion plastic pieces are currently floating around the world’s oceans (Eriksen et al. 2014). The chemical and physical properties of plastics, which make plastic materials versatile and useful in our everyday life, also make plastics a priority for marine litter management. The manufacturing process of plastic items requires the addition of often toxic additives to give plastics certain properties, whereas the hydrophobic nature of plastics means that they attract persistent organic pollutants found in the water (Andrady 2011; Deanin 1975; Koch et al. 2009; Rochman et al. 2013a; Tanaka et al. 2013). Cigarette butts, made of cellulose acetate, a form of plastic, also contribute to the accumulation and release of pollutants in the marine environment, as they have been found to be a point source of metal contamination, which can lead to the risk of acute harm to marine organisms (Moerman and Potts 2011).
Large pieces of plastic, called macroplastics, do not biodegrade but rather break down into continuously smaller pieces forming what is known as microplastics – plastic items smaller than 5 mm (Thompson et al. 2004; Arthur et al. 2009).
Encounters between marine litter and 693 species of marine organisms have been reported in literature, nearly 90% of which involve plastic litter (Gall and Thompson 2015). Such encounters have detrimental impacts on marine organisms. Macroplastics, such as plastic bags, six-pack rings and fishing-related items can be ingested by larger marine organisms causing blockages of the intestinal tract leading to starvation, and reduced fitness (Bjorndal et al. 1994; Ryan 1988; Spear et al. 1995). Marine organisms can also become entangled in these items, causing incapacitation, reduced preying/feeding abilities, lacerations, suffocation and drowning (Derraik 2002; Gregory 2009; Laist 1997). Microplastics can be ingested by marine wildlife transferring organic pollutants to their bodies, which can cause various health impacts, such as reduced energy reserves (Rochman et al. 2013b; Wright et al. 2013). Recent studies have shown that this can have important impacts on the food chain, as ingested microplastics have been identified in marine organisms destined for human consumption (Browne et al. 2008; Van Cauwenberghe and Janssen 2014). The possible effect that this can have on human health remains uncertain.
Over the years, several studies have investigated the amount and distribution of marine litter, and specifically plastics, in Europe and the Mediterranean (e.g. Aliani et al. 2003; Alomar et al. 2016; Baztan et al. 2014; Collignon et al. 2014; Eryaşar et al. 2014). Most recent estimates suggest that there are approximately 1455 tonnes of floating plastic in the Mediterranean, with microplastics - most with surface area of 1 mm2 - being ubiquitous (Ruiz-Orejón et al. 2016). An investigation of microplastic ingestion in the fish Boops boops in the Mediterranean has found that 68% of examined stomach samples from this species in the Balearic Islands had microplastics in them, at an average of 3.75 items/fish (Nadal et al. 2014), highlighting that Mediterranean marine biodiversity is under threat from the increasing presence of plastics (Deudero and Alomar 2015).
Information taken from: Loizidou, Loizides & Orthodoxou, (2018). Persistent marine litter: small plastics and cigarette butts remain on beaches after organized beach cleanups, Environ Monit Assess, 190:414, https://doi.org/10.1007/s10661-018-6798-9
