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Marine litter, or debris, is fundamentally linked to human activity. Through industrial activity and incorrect waste disposal, tonnes of debris enter the marine environment every single day, equating to roughly 10 million tonnes each year. Litter enters the marine environment directly from discarding on vessels, or through terrestrial sources, either through river or drainage systems (Derraik, 2002). This litter, not only creates unappealing aesthetics for a coastal area, but also causes many serious complications for marine life.
Impacts of Marine Litter
A wide range of marine animals, including seabirds, invertebrates, turtles, fish, and marine mammals, can easily become entangled in ghosts nets, resulting in serious, and often fatal, injury (Kuhn et al., 2015). Entanglement, poses a particular threat to marine mammals, like seals and dolphins. In Irish waters, over half of all seal deaths between 1994 and 1999 were as a result of accidental entanglement, be it in active fishing nets, or discarded debris (Rogan et al., 2001). Additionally, litter can be eaten by many sea creatures, causing digestive problems and eventual death. For example, 13 sperm whales found stranded in the North Sea area in 2015, were found to have eaten fishing nets, car parts, and even a plastic bucket, before stranding along the German coastline. Sea birds, are the most commonly threatened group by ingestion marine littler.
Current studies show that over 70% of seabirds have some form of marine litter in their stomachs, with plastics being the major contributor (Wilcox et al., 2015). On the seafloor, many benthic organisms can die from anoxia (lack of oxygen) as a result of marine debris smothering the substratum (Moore, 2008). This would pose serious dangers to areas like seagrass beds, found commonly around the Irish coast e.g. Barley Cove, Lough Hyne. Marine litter is a major problem affecting coastal areas however, plastics, and microplastics are the key contributors.
It has been shown that 10% of all plastics produced end up in the marine environment (Thompson, 2009). Not only do plastics pose considerable dangers to aquatic life due to entanglement and ingestion (which can lead to fatality), they are also extremely slow to break down and so persist in the ocean years after they have entered the water. If global plastic production were to halt now, the plastic in the world’s oceans would not disappear completely for at least 1,000 years (Van Sebille et al., 2012). From an Irish perspective, marine litter is a major issue with 57% of all coastal waters containing varying degrees of marine litter, with almost half of this being made up of plastics (Moriarty et al., 2016).
Floating plastics tend to aggregate within circulating ocean currents, also known as gyres, with the largest being found in the Pacific Ocean (Kaiser, 2010). This “garbage patch” is the largest of the 6 located in the oceans around in the world, including the Atlantic. It is thought that there is more plastic located in these patches than there is marine life (Van Sebille et al., 2012), with the majority of the plastics, comprising of smaller particles known as microplastics.
What are Microplastics?
Microplastics are smaller pieces of plastic (less than 5 mm in diameter) that are formed following a number of processes such as mechanical (abrasion), chemical (photodegradation), and biological (biodegradation). Microplastics can occur within the marine environment in the form of microbeads. Microbeads are very small pieces of manufactured polyethylene (PE) plastic that are utilised in everyday beauty and hygiene products (toothpaste, soap exfoliators). These micrometer-sized particles are too small for water treatment facilities to filter and process and as such they have entered our waters and now outnumber larger debris significantly (Browne et al., 2013).
What are the effects?
As UV radiation degrades these plastics to microscopic sizes, many of their toxic material components enter the marine food chain (Teuten et al., 2009) which in turn can impact on ecophysiological functions performed by marine organisms (Browne et al., 2013). In a recent study, Browne et al. (2013, p.2391) have shown that microplastics ingested by lugworms ‘accumulated large enough concentrations of pollutants or additives to reduce survival, feeding, immunity, and antioxidant capacity’. This has greater implications for marine organisms as a whole. The larger surface area of these particles also causes the aggregation of emerging contaminants, which can also enter the food chain (Lusher et al., 2015) resulting in knock-on effects to the physical health of people in coastal areas, and inland.
Good News for our Environment?
These numbers are rather alarming and the effects warrant a great degree of concern and action. Some positive steps have however been taken to combat the polluting of our marine environment with plastics through education, policy making and activism. Positive moves have for example been made by the USA and the UK in tackling the production and use of microbeads in cosmetics and other body care products.
Dr Peter Heffernan, CEO of the Marine Institute in Galway, has indicated that work is underway in Ireland to introduce legislation in the Dáil that proposes a ban on the manufacture and sale of products containing microbeads. Speaking on RTE’s Morning Ireland, Dr. Heffernan indicated that “Ireland, before the end of 2018, will introduce a ban, both on the manufacture and the sale, of any products containing microbeads (RTE, 2018).”
Plastic litter is causing huge problems for marine life but also the beauty of the country that draws so many tourists to our shores. Initiatives like Tidy Towns and An Taisce’s Clean Coasts, are helping to combat these problems. In 2014 alone, beach clean ups run by Clean Coasts noted thousands of individual pieces of litter on our nation’s beaches: over 5,000 plastic bottles, 4,000 aluminium cans, over 2,000 pieces of rope and netting (www2). Work like this does seem to be improving the situation in West Cork though. In 2015, 5 beaches were awarded Blue Flags, as a symbol of high quality bathing waters and beach cleanliness. These beaches are: Ring, Barleycove, Tragumna, Owenahincha, and Inchydoney, the last of which was also awarded Cork’s only Green Coast Award