Litter in our seas
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Image © Rastislav Stanik
In 2007, a rather unusual group of castaways washed ashore in northern France. They were rubber ducks that had completed a 15-year-long epic journey, started in January 1992 when a ship travelling from Hong Kong to the United States lost some of its cargo during a storm. One of the containers washed overboard held 28 800 toys, some of which had landed on the Australian and the east coast of the United States years earlier. Others had crossed the Bering Strait and the Arctic Ocean, to come ashore in Greenland, the United Kingdom and Nova Scotia.
Never-ending journey of plastics
Rubber ducks are not the only form of man‑made litter drifting in our seas. Marine litter consists of manufactured or processed solid materials (e.g. plastic, glass, metal and wood), which end up in the marine environment in one way or another.
Approximately 10 million tonnes of litter end up in the world’s seas and oceans every year. Plastics, more particularly plastic packaging waste such as beverage bottles and single-use bags, are by far the main type of debris found in the marine environment. The list goes on: damaged fishing nets, ropes, sanitary towels, tampons, cotton buds sticks, condoms, cigarette butts, disposable lighters, etc.
Mass production of plastics started in the 1950s and increased exponentially from 1.5 million tonnes per year to its current level of 280 million tonnes per year. Approximately one-third of current production consists of disposable packaging that is discarded within a year or so.
Unlike organic materials, plastic never ‘disappears’ in nature and accumulates in the environment, in the oceans in particular. Sunlight, salt water and waves split plastics into ever-smaller pieces. A disposable diaper or a plastic bottle can take around 500 years to split into such microscopic pieces. But not all microplastics are the result of the splitting process. Some of our consumer products, such as toothpaste, cosmetics and personal care products, already contain microplastics.
Ocean currents coupled with winds and the earth´s rotation gather these pieces, some of which measure mere microns (one millionth of a metre), and create large patches in areas called gyres. Depending on the size of the pieces, they might appear as a transparent type of ‘plastic soup’. These gyres are fluid and change in size and shape. The largest and most studied gyre, the North Pacific Gyre is estimated to have pulled 3.5 million tons of trash, affecting an area estimated to be twice the size of the United States. There are five other major whirlpools in our oceans where waste is also accumulating, including in the Atlantic.
Some pieces wash ashore to mix up with sand even in the most remote parts of the world. Others pieces become part of the food chain.
Where marine litter comes from
According to some estimates, about 80 % of the debris found in the marine environment comes from land-based activities. The source of marine litter is not necessarily limited to human activities along the coastline. Even when disposed of on land, rivers, floods and wind transport litter to the sea. Fishing activities, shipping, off-shore installations such as oil rigs and the sewage system contribute the rest.
There are some regional variations in the origin of marine litter. In the Mediterranean, Baltic and Black Seas, land-based activities generate most of the marine litter; in the North Sea, however, maritime activities are an equally significant contributor.
More plastics than plankton
The full extent of the impacts of marine litter is difficult to estimate. Marine litter has two key adverse effects on marine wild life: ingestion and entanglement.
Research conducted by Algalita, an independent marine research institute based in California, found in 2004 that marine water samples contained six times more plastic than plankton.
Given its size and prevalence, marine animals and sea birds mistake marine litter for food. More than 40 % of existing species of whales, dolphins and porpoises, all species of marine turtles, and around 36 % of sea birds species are reported to have ingested marine litter. Ingestion is not limited to one or two individuals. It affects schools of fish, as well as flocks of sea birds. For example, over 90 % of Fulmar sea birds that washed ashore dead in the North Sea had plastic in their stomach.
A stomach filled with indigestible plastic can prevent the animal from feeding, ultimately starving it to death. The chemicals in plastics can also act as poison, and depending on the dose, they can permanently weaken or kill the animal.
Larger pieces of plastic also pose a threat to marine life. Many species, including seals, dolphins and sea turtles, can get entangled in plastic debris, and fishing nets and lines lost at sea. Most of the entangled animals do not survive, as they cannot get up to the water’s surface to breathe, escape from predators or feed themselves.
Tip of the iceberg
Marine litter is a global problem, and reliable data are hard to collect. Currents and winds move visible pieces around, which might result in the same debris being counted more than once. Moreover, only a small portion of marine litter is believed to be floating or to wash ashore. According to United Nations Environment Programme (UNEP), only 15 % of marine debris floats on the sea surface; another 15 % remains in the water column, and 70 % rests on the seabed.
The ‘invisible’ part of the debris continues to affect the overall health of the marine environment. Around 640 000 tonnes of fishing gear is estimated to be lost, abandoned or discarded globally. These ‘ghost nets’ continue catching fish and other marine animals for years and decades.
Moreover, some of the fish species ingesting plastics are regulars on our plates. By consuming seafood exposed to plastics and their oil-based chemicals, human health is also put at risk. The human health impacts are not fully clear.
Coastal communities most affected
More than 40 % of the EU population lives in coastal regions. In addition to its environmental costs, marine litter has also socio-economic costs, affecting mostly coastal communities. A clean coastline is vital for beach tourism. On average, 712 items of litter are found on a 100-m stretch of beach on the Atlantic Coast. And without action, marine litter accumulates on the beach. In order to boost the appeal of their bathing sites to tourists, many communities and businesses must clean up the beaches before the start of the summer season.
There are no comprehensive estimates of the total cost of marine litter on society. Likewise, it is difficult to estimate the loss to the local economy due to potential visitors choosing other sites. But there are examples of concrete costs for clean-up activities, quantified in monetary terms. In the United Kingdom, municipalities spend approximately EUR 18 million per year for beach clean-ups.
Clean-up activities might help collect larger pieces and improve the aesthetics of the area, but what about small pieces? According to Kommunenes Internasjonale Miljøorganisasjon (KIMO), an international organisation bringing together local authorities around marine pollution issues, around 10 % (by weight) of the strandline material consists of plastics. Because of their small size, it is often impossible to differentiate these from sand.
Tackling marine litter: start with prevention
Although marine litter is only one of the pressures on the health of the marine environment, it is a growing concern. The accumulation and long endurance of plastics in nature complicates the issue further.
Marine litter is a cross-border problem; once it enters the sea, it has no owner. This makes its management difficult and highly dependent on good regional and international collaboration.
Some EU legislation targets marine issues directly. For example, the EU’s Marine Strategy Framework Directive adopted in 2008 identifies marine litter as one of the areas to tackle in order to achieve good environmental status for all marine waters by 2020. Following up on these EU directives and the global commitment expressed at the Rio+20 UN Sustainable Development Conference in 2012, the EU’s 7th Environment Action Programme (2014–2020) foresees establishing a baseline and setting a reduction target.
Similar to overall waste management, the starting point for tackling marine litter is prevention. How can we prevent litter? Do we need plastic bags every time we go shopping? Can some of our products and production processes be designed so that they do not contain or create microplastics? Indeed, they can.
(c) Ani Becheva / EEA Waste•smART
Action starts on land
The next step is to take action on land, before litter reaches our seas. To this end, the EU has policies and legislation aimed at improving waste management, reducing packaging waste and increasing recycling rates (of plastics in particular), improving wastewater treatment, and using resources more efficiently in general. There are also directives drawn up to help curb pollution from ships and ports. Improving the implementation of waste prevention and reduction policies can potentially reap enormous benefits.
But what about the litter already affecting our seas and oceans? Marine litter has been accumulating in our seas for years. Some pieces have sunk to the bottom, while others are moving around with ocean currents. It is nearly impossible to imagine how we can clean it all up.
Several ‘fishing for litter’ initiatives are in place, where vessels collect marine litter — similar to municipal waste collection on land. However, the methods being used fail to collect litter below a certain size. So the problem of microplastics remains unsolved. Moreover, given the scope of the problem and the size of our oceans, such initiatives are too limited to result in real improvements.
The same might be said about clean‑up activities on beaches and coasts. Nevertheless, such initiatives are a good way to raise awareness of the issue and engage citizens in the tackling of the problem of marine litter. At the end, it may simply be a question of numbers. As the number of volunteers joining such activities increases, the better we might be at prevention.
The EEA has developed Marine LitterWatch, which includes an app to monitor marine litter on Europe’s beaches. The app, available for free, allows beach clean-up communities to collect data in a way that can help improve our knowledge about marine litter. It also allows interested parties to find clean-up initiatives nearby or to create their own community.
For references, please go to http://www.eea.europa.eu/signals/signals-2014/close-up/litter-in-our-seas or scan the QR code.
PDF generated on 23 Feb 2017, 08:17 PM