Caroline Hand explores the damage that waste plastics are doing to our seas and the very serious threat to the survival of many species of marine life.
The seafarer’s tale
When Captain Charles Moore sailed from Hawaii to California in 1997, he brought back an alarming report — a huge floating island of plastic waste, the size of Texas. The Great Pacific Garbage Patch had been discovered and has since become a symbol of man’s wastefulness and our abuse of the oceans. More recent headlines declared the Garbage Patch to be something of a myth: the fact of the matter is that larger pieces of plastic are scattered thinly over a large area rather than being concentrated in a dense layer.
However, beneath the ocean’s surface float myriad minute particles of plastic, highly dangerous to marine life despite being invisible to the naked eye. Citizens of the UK and USA have responded to the threat by supporting the bans on microbeads and carrier bags, but to tackle plastic pollution effectively, the global community will have to turn its attention to the lack of basic waste infrastructure in the developing world.
Wildlife harmed by plastic
Distressing images of injured marine animals and birds are only too easy to find on social media. A turtle with a drinking straw impaled in its head; a whale entangled in a discarded fishing line; an albatross feeding plastic litter to its chick. Such items of plastic waste are a danger to marine life all over the world. Whales, dolphins, seals, puffins and turtles have all been found with plastic obstructing their breathing or blocking their stomachs. On the remote Pacific atoll of Midway, albatrosses bring in 10,000 pounds of plastic — which they mistake for squid — each year, from as far afield as Alaska. They eat it and feed it to their chicks who are likely to starve as a result. The manager of the island’s wildlife refuge commented that “anywhere you see a big pile of plastic but nothing else, that’s where an albatross died”.
Fortunately there is an increasing level of public awareness of this problem and, in developed countries at least, people have responded well to campaigns to tackle plastic litter. Thanks to the 5p tax on single-use carrier bags, littering in the UK has been reduced considerably. And over in Northern California, a conservationist has persuaded schoolchildren to stop littering by showing them the contents of albatross stomachs. The plastic rings from drink can six-packs, which used to choke marine animals, are now photodegradable so they no longer pose such a threat.
Various environmentally-aware businesses have taken the oceans to heart. Interface, the carpet tile manufacturer renowned for its sustainable ethos, sponsors the Net-Works project which collects discarded fishing nets in Africa and the Philippines then recycles the plastic. This creates work for local communities as well as protecting marine life from entanglement in the nets. In the Philippines, 61,845kg of nets have been collected, of which 41,803kg were recycled into carpet.
Adidas has joined forces with the charity Parley for the Oceans to create a range of trainers made from 95% ocean plastic. The waste is collected from the shoreline of the Maldives and along 1000 coral islands off the western coast of India.
Disposable water bottles are frequently found among the marine garbage. Selfridges, the famous London department store, has been running its Project Ocean campaign for the last five years. Along with promoting the consumption of sustainably caught fish, it has removed all plastic bags and single-use water bottles from the store. Instead it provides a water bar and sells fashionable reusable bottles.
Microplastics: the bead ban
Both the UK and US Governments have promised to ban the use of microbeads in cosmetics from 2017. These tiny beads are used in everyday products such as toothpaste and exfoliating scrub, and a single use of some products can result in 100,000 beads being flushed down the drain. Many are small enough to bypass the filters at sewage treatment works and enter the aquatic environment, ending up in the oceans where they are ingested by fish and other marine animals.
The banning of these beads is a step forward, but alone will not eliminate the problem of microplastics in the ocean. Other non-cosmetic products contain microbeads. Even the synthetic fibres of our clothes release microplastics: a recent study by researchers at Plymouth University found that acrylic was the worst offender, releasing nearly 730,000 tiny synthetic particles per wash.
When a plastic bag or other item of waste enters the ocean it does not biodegrade, but instead breaks down into tiny fragments. These float below the surface in the upper layer of the water and are readily ingested by fish and other marine animals. Since it is indigestible, the plastic builds up in the animal’s digestive tract. Recent research has revealed the serious harm done by these tiny particles.
In one study published in the journal Science, larval perch with access to microplastic particles ate only the plastics, ignoring their natural food of plankton. Fish born into an environment rich in microplastics had reduced rates of hatching and development to maturity. The perch studied also ignored the chemical signals that would normally warn them of the presence of predators. Once pike (predators of perch) were introduced into the environment, the plastic-eating perch were eaten four times more quickly than their naturally-reared relatives.
Another study discovered that crabs which were fed a diet containing 1% polypropylene rope microfibres had a reduced capacity to take in energy from their food and their potential for growth was restricted.
Other studies have linked plastics to physiological stress, liver cancer and endocrine dysfunction in the fish that ingest them. Plastic can reduce fertility in both male and female fish. Even the creatures at the bottom of the food web such as lugworms and amphipods are affected by plastic.
Little can be done to remove the microplastic particles that are already floating in the sea or have sunk to the ocean floor. The priority is to prevent additional plastic waste from entering the marine environment and causing further harm.
How much plastic is in the ocean?
According to a recent report, (Stemming the Tide, published by Ocean Conservancy and the McKinsey Centre for Business and Environment) the ocean may already contain upward of 150 million tonnes of plastic, based on global plastic production since 1950. If current trends continue, this will rise to 250 million tonnes by 2025, representing one tonne of plastic for every three tonnes of fish. The Mediterranean alone currently contains 1455t of floating plastic. We are currently dumping the equivalent of one waste truck’s worth of plastic packaging into the ocean every minute, and unless effective action is taken this is predicted to increase to four per minute by 2050. At that point there would be more plastic than fish in the sea.
Where does it come from?
Some of the waste is associated with shipping, for example, discarded fishing nets and lines, but around 80% of marine plastic originates on land. Currents carry the waste far from its point of origin to the “garbage patches” in the North Atlantic, South Atlantic, North Pacific, South Pacific and Indian Oceans.
While it is undoubtedly more sustainable to reuse a water bottle rather than dispose of it, the fact is that bottles disposed of in the UK are not likely to end up in the ocean. They will enter the municipal waste stream and, if put in the recycling bin, are likely to be recycled into another bottle. At worst, they will end up in landfill. If plastics are to be kept out of the oceans, attention must turn to other parts of the world where plastic waste is not managed adequately.
On a global scale, only 14% of plastics are recycled, with a smaller percentage going for energy recovery. Forty-two percent of plastic waste is landfilled and the remaining 32% escapes to the environment.
An estimated 55–60% of the “leaked” plastic comes from five countries — China, Indonesia, the Philippines, Thailand and Vietnam — all rapidly growing economies where the waste infrastructure has not been able to keep pace with consumer demand for safe, disposable products. A study of these countries indicated that 75% of the plastic reaching the ocean comes from uncollected waste, while the remaining 25% leaks from within the waste management system itself. This leakage emanates from unregulated dumps and also from poorly located and managed landfills, particularly those sited in coastal zones. Media photographs illustrating the “Great Pacific Garbage Patch” are most likely to have been taken in Manila, Philippines, where little boats cut their path through a dense mass of floating plastic.
The research found that only 20% of the plastic waste has sufficient value for waste pickers to collect it. Low-value plastics such as films and composites, which made up 61% of the waste surveyed, are left to leak into the environment. What can be done?
Improve waste infrastructure
The report Stemming the Tide focuses specifically on the five Asian countries responsible for most of the leakage. It sets out a list of practical recommendations such as better enforcement of environmental legislation to stop illegal dumping; siting waste dumps away from the coast; and improving waste collection from the current average rate of 40% to 80%. In contrast with the UK situation, recycling is unlikely to be the best solution due to the lack of optical sorting technology to identify and segregate different polymers.
Develop a biodegradable plastic
Taking a different angle, a recent report for the Ellen MacArthur Foundation, The New Plastics Economy, recommends the development of a truly biodegradable plastic. This report is more pessimistic about the likelihood of improvements to waste collection infrastructure in developing countries and presumes that large quantities of plastic will continue to enter the ocean. The most practical solution is therefore to ensure that discarded packaging breaks down completely to prevent ingestion by marine animals. Sadly we are still a long way from achieving this goal and a technical breakthrough is needed. One small success story is the Ooho! edible water bottle — made from extracts of seaweed and calcium chloride, it looks like a silver bubble which encapsulates a drink of water.
Action on the global scale
The New Plastics Economy looks beyond Asia to recommend strategies for reducing plastic consumption on a global scale and increasing the proportion which is reused and recycled. International product standards could be developed with recycling in mind. If there was greater transparency and consistency in formulations (particularly when it comes to potentially hazardous chemical additives), it would become feasible to recycle far more packaging into food-grade plastics. Clear, standardised labelling — perhaps using chemical markers — would help in this. Plastic manufacturers are challenged to remove harmful additives from their products (or at least be more transparent about their use) in order to mitigate the damage to sea life.
This report also recommends the increased use of durable, reusable plastic packaging which would be of value to the waste pickers in developing countries.
Other pollution threats
While today, plastic is the marine pollutant with the highest profile, other types of pollution have not gone away. The dumping of chemicals at sea has been illegal for decades but oil and other hazardous substances still find their way into the marine environment from urban runoff. Persistent organic pollutants bioaccumulate up the food chain, and are found in the tissues of mammals and birds in the earth’s remotest places.
Diffuse pollution from agriculture is a major threat to marine life in some parts of the world. Nitrogen-rich fertilisers are washed into streams and rivers and are eventually deposited in estuaries, bays and deltas. The over-fertilisation of these coastal waters causes massive blooms of algae to grow, and when the algae decompose, all the oxygen in the water is consumed in the process. This leaves the water as a dead (anoxic) zone where no marine life can survive. Over 400 of these dead zones have been identified, most of which are located along the eastern coast of the USA, the Baltic coastlines, Japan and the Korean Peninsula.
Each summer a dead zone forms in the Mississippi Delta and grows to the size of Massachusetts. Even worse is the situation in the Baltic Sea, where the eutrophication problem is intensified by overfishing of Baltic cod. Cod eat sprats, which eat microscopic zooplankton, which in turn eat algae. Fewer cod and more sprats mean more algae and less oxygen. As the dead zones spread to the cod’s breeding ground, the cod is further endangered. In response to this problem, the EU is co-ordinating a strategy in partnership with the Member States that border the Baltic Sea.
The situation in the Baltic draws attention to another major problem: overfishing. It is a very serious threat to the survival of many species of marine life and to the human communities which depend on fishing for their livelihoods and food. The 19th century evolutionist Thomas Huxley notoriously said: “Probably all the great sea fisheries are inexhaustible; that is to say that nothing we do seriously affects the number of the fish.” He could not have been more wrong.
Last reviewed 7 February 2017