Marine Plastic Pollution2021-05-01T20:10:40-05:00

Marine Plastic Pollution

By 2050, it is estimated that there will be more plastic in the ocean by weight, than fish.

Plastic Debris

The problem

Plastic Debris can be found throughout the ocean. The world produces over 280 million tonnes of plastic each year. Of this, it is estimated that 3% make their way into our ocean. Based on 2010 estimates this is approximately 8 million tonnes. This plastic has been found in the most remote areas on the planet, including at the bottom of the Mariana trench, uninhabited islands, and in the Arctic. It has also found its way into the marine ecosystem, with ¼ of fish being estimated to have plastics in their stomachs.

Where does the plastic come from?

80% of this plastic comes from land-based sources, mainly stemming from rivers. The other 20% comes from marine-based sources like shipping, fishing and tourism. These sources can be further split into domestic and industrial sources. Hotspots refer to the core areas which contribute to leaking plastic into the ocean, including particular plastic polymers, industries, regions and waste management stages.

primary plastic production by industrial sector 2015

 Land-based sources of Plastic Debris

Land-based sources of plastic pollution primarily stem from poor waste management. 300 million tonnes of plastic are produced each year. Mismanaged waste can be either littered, or disposed of inadequately. Particular elements within the waste management system have a larger impact on plastic leakage. This includes how the waste is generated, segregated, and collected, and the infrastructure that manages this waste.

For countries in the Global North, the plastic thrown away is generally exported to countries in the Global South. This imposes asymmetrical polluting effects on countries like Indonesia. This is primarily due to this exporting of plastic waste. South East Asia is now the primary destination for exported plastics, due to legislation ambiguities which inhibit the tracking of plastics coming into the country. The UN has researched where this land-based plastic comes from, and what sources contribute the most to plastic leakage. Certain plastic applications lead to key hotspots, and these include plastic bags, plastic straws, and drink bottles.

Lifecycle of plastic and plastic products with information on sources of losses of primary microplasti

Source: IUCN

Land-based sources of plastic debris can enter the ocean through inland waterways, or through wind or tides.

Fishing Gear is hazardous to a wide range of wildlife.

 Marine-based Sources of Plastic Debris

Marine-based sources contribute to 20% of the plastic pollution entering the ocean. This includes pollution from normal operations of shipping or fishing, accidental pollution, or deliberate pollution. Fishing nets and other fishing gear are a key source of marine-based plastic. This is known as ghost gear, or Abandoned, Lost or otherwise Discarded Fishing Gear (ALDFG). Fishing gear is created to trap marine organisms, so when it is lost at sea it continues to do this in a process called ghost fishing. This type of marine pollution can occur accidentally or intentionally. Fishing gear lost from boats can account for 10% of plastic currently in the ocean. The plastic problem from ALDFG is only increasing as the fishing industry gets larger.

 Where does this plastic go, and what damage does it cause?

Plastic has been found in the most remote areas on the planet, including at the bottom of the Mariana trench, uninhabited islands, and in the Arctic. It has also found its way into the marine ecosystem, with ¼ of fish being estimated to have plastics in their stomachs.

The majority of plastic is less dense than water, but estimates of plastic which is in surface water are far lower than what is estimated to enter our oceans each year. This report by Erisksen et al. estimates the amount of plastic in the global oceans to be at 250,000 tonnes. This discrepancy between plastic released and plastic estimated to be floating in the ocean is known as the ‘missing plastic problem’. One explanation is that UV light and ocean waves break large pieces of plastic into microplastics. Another is that deep-sea sediments contain the missing plastic. New research suggests that this missing plastic may be washing up on our shorelines, and has found that the majority of this missing plastic is buried along our shores. Accumulated plastics along these shorelines can date back to the 1950s.


Gyres are the convergence points of the global ocean currents. The term has become synonymous with the aggregation of plastic waste in these zones. Plastic which enters the ocean from land or marine-based sources will end up carried by currents and collecting in these Gyres. Gyres have a high density of floating plastic and microplastic. Gyres can also contain high amounts of ghost gear. There are five main plastic Gyres or Garbage Patches, these are: the Indian Ocean, North and South Atlantic and North and South Pacific Gyres. The largest of these is known as the Great Pacific Garbage Patch. Once plastic reaches these patches, it becomes trapped and can start to break down further into microplastics.

Damage to Marine Life and vulnerable ecosystems

Macroplastics can have a significant impact on marine fauna. We have all seen images of marine animals with beer rings around their necks, or plastic in their stomachs. Some species affected are endangered, which leads to a larger issue for conservation. Macroplastics can also damage vulnerable ecosystems like coral reefs. Ghost gear is particularly damaging here, as tangled fishing nets can smother these vulnerable ecosystems, and entangle endangered species. Ghost gear also presents an economic problem, as ghost fishing impacts on fish stocks.

The spread of plastic: Henderson Island

Henderson island is an uninhabited island in the Pacific Ocean, which in 2017 recorded 37.7 million debris items, with 27 new items estimated to be added to this total daily. Marine Scientists have estimated that this island has the highest density of anthropogenic debris in the world. This plastic harms native flora and fauna, some of which are unique to this land. This damages the entire ecosystem of the island. The island has a high level of biodiversity for its size, and plastic pollution threatens this biodiversity. This is a prime example of the extent to which plastic has become ubiquitous in the ocean, and the transboundary nature of the problem.


What are microplastics and where do they come from?

The problem of ocean plastics is not just limited to the plastics you can see. Microplastics are tiny pieces of plastics less than 0.2 inches, which arise from the breakdown of larger pieces of plastic, or corporate use of plastic and its subsequent disposal. Due to their size, and their aesthetic similarities to food for sea life, they are frequently ingested by ocean wildlife. From there, they enter our own bodies through water, salt, and fish. Storms, water run-off and disposal of plastic waste into the ocean transport microplastics to the sea, a process amplified by the inability of water screening processes to filter them from water systems. The health implications of microplastics range from what we know — digestive problems, toxin-related health issues – to what we have yet to find out.

One of the most nefarious realities of our microplastic problem is the tendency to treat microplastics with the “out of sight, out of mind” mindset. When we cannot see them, it is more difficult to galvanise people against microplastics, and more difficult to assess their implications. Without seeing them, the average citizen can find it difficult to know where we can find them. This is why microplastics have been present in cosmetics and microfibres from washing clothes for decades.

Primary microplastics include microplastics which are already broken down before they are released into the environment, for example microbeads in cleansers, exfoliants, and other personal care products.

Primary microplastics are estimated to make up 15-30% of microplastics

Banning microbeads in cosmetics, as has been done in Ireland and the Netherlands, to name a few, is a step towards the reduction of microplastics in the ocean, per the OECD. However, microplastics come from a variety of sources and require a larger reduction of plastic usage as a whole to change the amount of microplastics in our environment. 

Secondary microplastics come from the photodegradation and misuse of plastic and plastic waste, whereby plastic items are broken down into microplastics, for example fishing nets, plastic bags, and clothes.

The fashion industry in particular is a major contributor to marine ocean plastics, through the usage of synthetic fibres in clothing. Washing machines slowly break down synthetic fibres, and they pass into our ocean system via pipes. Aside from the effects of waste from mass production and disposal of clothes, the impact of synthetic fibres on the environment is a significant external cost imposed by the fashion industry.

Secondary microplastics estimated to account for 69-81% of microplastics found in the oceans

Breakdown of marine plastic debris  is a form of secondary microplastics which occurs when plastic particles are broken down by the weather i.e. water, sunlight, the sea, or other non-natural forces, forming microplastics. Examples of this include the gradual erosion of plastic waste, synthetic fibres from clothes breaking down in the wash and passing into the sea via water infrastructure.

Ship coatings are a particularly notable secondary source of microplastics originating from busy waterways. Areas with heavy shipping traffic tend to have higher levels of microplastics due to the breakdown of plastic coating from ships. Similarly to the particles left over from wear and tear of tyres, garments, or other objects on land, the use of ships over time leaves a trail of microplastics in the sea, from the weathering of ships by the sea. German scientists confirmed this in 2016 with a study of the German Bight in the North Sea. Along shipping routes. particles of PVC, polycarbonates and acrylates accounted for a much higher percentage of microplastics than traditional sources.

  • In short, microplastics originate from the intentional breakdown, or unintentional wear and tear of plastic, even when plastic is a small component of a product, as in clothes. Further evidence of microplastics in transport and urban life include breakdown of tyres, plastic from paint and road markings, urban dust. All can be transported to land, sea, and waterways by rain and wind.

Negative Impacts of Microplastics in the Ocean

The impacts of microplastics are still not fully understood, given their relative novelty to scientific knowledge, compared to other bodies of research. However, some aspects of the impacts of microplastics are known….

Toxins: The components which make up microplastics have known toxic effects. Microplastics themselves have unknown toxicity, but the impacts of ingesting the components that are known to be toxic suggests the prospect of harmful effects on the marine and land life which ingest them.

Fishlife damage: While conclusive evidence on the nature and extent of microplastics’ impact on the survival and biological functions of marine life is still emerging, recent work by the IAEA showed that a third of studies on fishlife showed microplastics impacting their neurological and biological functions. This is particularly dangerous given that microplastics are so small that they are in danger of being absorbed into tissues, and affecting the function of vital organs such as digestive tracts.

While not enough evidence exists to prove a damaging effect on fish at population levels, this is still significant enough to warrant concern, and caution, given that effects of such processes are often more long-term developments.

Human Life: Human ingestion of microplastics is largely agreed upon by scientists. Microplastics have been recorded in human food consumption and stool samples. The effects of this are developing, with toxicity being investigated as a potential source of concern.

How do we solve the plastic pollution problem?

There are many initiatives to clean beaches but the problem needs tackling at its source.

Because plastic is a transboundary issue, and once it enters the ocean and is brought beyond national jurisdiction, no one organisation or country is responsible for cleaning plastic from the ocean in international waters. Solving the plastic pollution problem requires multi-stakeholder collaboration. Plastic needs to be removed from the ocean, at the same time plastic needs to stop entering the ocean. This gives way to a multitude of solutions at different levels. Without these solutions it is estimated that 99 million tonnes of plastic waste could enter the ocean by 2030. The main problem with governing plastic pollution is that there is no simple solution.

Legislative solutions

Solving the marine plastic problem requires a shift in production and consumption patterns, which would contribute to achieving the Sustainable Development Goals. SDG 12, and SDG 14 are the main UN SDGs which tackle marine plastics. There are many things that countries and regions can do to tackle plastic. Identifying the hotspots for plastic leakage can help governments produce effective policy which directly tackles the plastic problem. For example, the EU has banned the use of single use plastics, which are a core plastic hotspot. Changing which plastics are produced, and creating sustainable alternatives to products currently in existence is a core element in tackling the plastics problem.

Managing plastic pollution requires the application of the Polluter Pays Principle. This principle maintains that those who produce pollution should pay the costs of managing it. The principle forms the basis for marine waste regulation in many countries, including EU policy on banning single use plastics. The new EU plastics regime extends this principle to fishing gear. This means that manufacturers of plastic fishing nets bear the costs of recovering these nets. The EU has also adopted rules on exporting and importing plastic waste, which bans the export of non recyclable plastic waste to non-OECD countries.

Another example of international plastic governance is the Marpol Convention, which provides regulations for the prevention of pollution from ships. The Global Programme of Action for the Protection of the Marine Environment from Land Based Activities is the only global intergovernmental mechanism which directly addresses the interconnectivity between pollution on land and marine pollution, and aims to deal with land-based sources of marine pollution as a common goal. Article 192 of the UN Convention of the Law of the Sea (UNCLOS) states that ‘States have the obligation to protect and preserve the marine environment’, which can form the basis for plastic pollution legislation. Regional policies include the Regional Action Plan on Marine Litter established by the Coordinating Body on the Seas of East Asia (COBSEA), which highlights national, regional and local policies that can be implemented to coordinate solutions to the plastic problem.

Non-profit organisations can take action in this area by lobbying governments to enact legislation which regulates the production of plastic and improves waste management.


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