The Ocean's Plastic Crisis: Understanding Its Causes

Plastic pollution in the ocean is a pressing global crisis that is having a devastating impact on marine wildlife and ecosystems. It is caused by a variety of factors, including improper waste disposal, plastic waste from ships, and discarded fishing gear. Rivers are the primary source of ocean plastic pollution, with around 80% of plastic in coastal waters originating from land-based sources such as litter, construction trash, and industrial facilities. However, the Great Pacific Garbage Patch, the most polluted area in the ocean, is largely comprised of plastic from fishing activities. The durability of plastic means that once it enters the ocean, it persists for long periods, accumulating in massive circular currents called gyres. This plastic pollution leads to the ingestion, suffocation, and entanglement of marine species, causing fatalities and threatening biodiversity.

Plastic waste from land-based sources

Rivers are the primary source of ocean plastic pollution from land-based sources. The Jambeck Research Group estimates that the amount of plastic entering the ocean from land-based sources is 20 to 2000 times more than what is visible on the ocean surface. This is because not all plastic floats; some sink to the seafloor or are suspended in the water column.

The probability of plastic entering the ocean varies with the climate, terrain, land use, and river basin characteristics. For instance, the Philippines has a 7% probability of mismanaged plastic waste entering the ocean, while China has a 0.2% probability. Coastal cities in middle-income countries are the world's plastic emissions hotspots. This is because, in these countries, plastic consumption is increasing, but there is a lack of adequate waste management systems to handle the increased consumption. People in high-income countries consume the most plastic, but effective waste management systems mean that plastic pollution is kept out of the natural environment.

The specific plastic items that contribute to ocean plastic pollution include cigarette butts, food wrappers, beverage bottles, straws, cups, plates, bottle caps, and single-use bags. These items are often consumed and quickly discarded, and if they are not properly disposed of or managed, they can end up in the ocean. Abandoned fishing nets also contribute significantly to ocean plastic pollution.

To address the issue of plastic waste from land-based sources, it is crucial to focus on waste management and collection. This includes developing sound waste management infrastructure in nations that lack it, as well as raising awareness about the importance of reducing plastic use and properly disposing of waste.

Plastic waste from ocean-based sources

Marine wildlife is suffering the most direct and damaging effects of ocean plastic pollution. Plastic is durable, which means that once it enters the ocean, it persists there for long periods. The oldest pieces of plastic found in clean-up catches date back to the 1960s, and marine life continues to bear the consequences.

While most of the plastic in our oceans comes from land-based sources, a significant amount, estimated at between 20% and 30%, comes from marine sources. This includes fishing nets, lines, ropes, and abandoned vessels.

Fishing gear is a major source of plastic pollution in the Great Pacific Garbage Patch, located in the North Pacific Ocean between Hawaii and California. Research shows that about 80% of the plastic in the GPGP comes from fishing activities at sea. Abandoned fishing nets make up a large portion of the plastic in the oceans, and microfibers shed from these nets are another problematic form of microplastic. These fibers can absorb harmful pollutants like pesticides, dyes, and flame retardants, which are then released into the ocean.

In addition to fishing gear, plastic waste from ocean-based sources can also come from boats and ships. Intentional littering or improper disposal of trash can cause marine debris, and littering from boats and ships can contribute to this problem.

While it is challenging to determine exactly how much plastic is in the ocean, scientists estimate that about 8 million metric tons of plastic entered the ocean in 2010. This is equivalent to the weight of nearly 90 aircraft carriers, and the problem is only growing. To address this issue, a global approach to reducing plastic waste and managing it appropriately is necessary.

Plastic ingestion by marine animals

Marine wildlife is suffering the most direct and damaging effects of plastic pollution in oceans. From fish to turtles, seals, crustaceans, microorganisms, and many other forms of life, the damage caused by plastic pollution to marine animals is increasingly visible.

Fish in the North Pacific ingest 12,000 to 24,000 tons of plastic each year, which can cause intestinal injury and death and transfer plastic up the food chain to bigger fish, marine mammals, and human seafood eaters. A recent study found that a quarter of fish at markets in California contained plastic in their guts, mostly in the form of plastic microfibers.

Anchovies are another example of a species that consumes microplastics. As they are eaten by larger fish, the toxins in those microplastics could be transferred to fish consumed by humans. A study by Savoca found that anchovies responded to the odour of plastic debris with foraging behaviour typical of their feeding practices. They did not respond to clean plastic.

The impact of plastic ingestion on marine animals is not limited to physical harm but also extends to their reproductive rates. On many beaches, plastic pollution is so pervasive that it affects turtles' reproduction rates by altering the temperature of the sand where incubation occurs.

Overall, plastic ingestion by marine animals has severe consequences, including internal injuries, starvation, and death, and it is a pressing issue that needs to be addressed to protect marine ecosystems and the animals that inhabit them.

Plastic entanglement of marine animals

Plastic pollution in the ocean is a pressing issue that poses a direct threat to marine life. One of the most significant consequences of this pollution is the entanglement of marine animals, which has increased by 40% in the last decade. This issue affects a wide range of creatures, from smaller animals like dolphins, seals, and sea turtles, to larger whales. The impact of plastic pollution on marine wildlife is twofold: the direct physical impact of entanglement, and the ingestion of plastic debris, which people often mistake for food.

Plastic debris in the ocean, including abandoned fishing nets, poses a significant threat to marine animals, who can become entangled and trapped. This entanglement can lead to immediate drowning for smaller creatures, while larger animals may suffer from exhaustion and infection. The impact of entanglement varies depending on the size and weight of the gear or plastic waste. For example, smaller animals like sea turtles, seals, porpoises, and smaller whales may drown immediately if entangled in large or heavy gear. On the other hand, larger whales are generally able to pull themselves and the gear off the ocean floor and are not at immediate risk of drowning. However, they face other risks, such as exhaustion and infection.

Fishing gear and nets are a major source of plastic pollution in the ocean and pose a particular threat to marine animals through entanglement. This issue is especially prevalent in the Great Pacific Garbage Patch, located in the North Pacific Ocean between Hawaii and California. Research indicates that about 80% of the plastic in this area comes from fishing activities. Abandoned fishing nets and gear can entangle marine animals, leading to injury or death.

The impact of plastic pollution on marine life is not limited to entanglement. Marine animals often mistake plastic debris for food, leading to ingestion, which can be fatal. This issue is widespread, with over half of the reviewed papers in a recent study documenting the ingestion of plastic by marine animals, impacting 663 species. Additionally, plastic pollution can transport invasive species and harmful chemicals, further endangering marine life and ecosystems.

The accumulation of plastic in the ocean is a result of the material's durability and lack of biodegradability. Plastic can persist in the ocean for long periods, with pieces from the 1960s still being found today. The problem is exacerbated by inadequate waste management systems, particularly in middle-income countries, where plastic usage is increasing. To address this issue, it is crucial to reduce plastic use, improve waste management practices, and support global efforts to reduce plastic production and eliminate harmful products and chemicals.

Lack of adequate waste management systems

A lack of adequate waste management systems is a significant contributor to plastic pollution in the ocean. This issue is particularly prevalent in middle-income countries, where plastic consumption is increasing but waste management systems struggle to keep up with the rise in consumption. This results in a substantial amount of plastic waste being improperly disposed of or left uncollected, ultimately ending up in the ocean.

Inadequate waste management systems can take on various forms, each contributing to the plastic pollution crisis. For instance, many communities lack access to proper waste infrastructure, such as functioning recycling centers or efficient trash collection services. This deficiency leads to a buildup of trash and recyclable materials, which eventually find their way into nearby water sources and, consequently, the ocean. Even when waste centers or incinerators are present, they often lack the capacity to handle the volume of waste generated, as seen in the case of the Bantar Gebang landfill in Indonesia, which receives 7,000 metric tons of waste daily but lacks the infrastructure to manage it effectively.

The absence of adequate waste management systems also extends to the global trade of plastic products and waste. There are instances where plastic waste is exported to locations that lack the infrastructure to manage it safely and sustainably. This practice further exacerbates the plastic pollution crisis, as the receiving countries may not have the capacity to process the additional waste, leading to increased plastic emissions into the ocean.

Furthermore, the lack of waste management and infrastructure contributes to the proliferation of plastic pollution by hindering the recycling process. Without proper systems in place, recyclable materials are often not collected or sorted effectively, reducing the likelihood of them being recycled. This issue is evident in Indonesia, where only 10% of plastic is recycled due to limited recycling capabilities, in stark contrast to Australia, which has a more advanced waste management system and a larger-scale recycling facility.

The impact of inadequate waste management systems is not limited to the environment; it also has economic repercussions. The accumulation of plastic waste and the subsequent pollution can negatively affect various sectors of a country's economy, including small and medium-sized enterprises, tourism, fisheries, and agriculture. This impact is particularly pronounced in coastal cities within middle-income countries, which have become hotspots for plastic emissions due to their proximity to rivers and oceans.

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