Plastic Pollution In Coral Reefs: A Growing Concern

Plastic pollution is a significant threat to coral reefs, with recent studies finding plastic debris smothering 92% of coral reefs examined. Plastic debris has been found to promote the development of diseases in coral reefs, with the risk of disease up to 22 times greater on a reef polluted by plastic. The impact of plastic on coral reefs is widespread, with plastic found in 77 out of 84 coral reefs surveyed in the Pacific, Atlantic, and Indian Oceans. The presence of plastic in coral reefs is due to the continuous flow of plastic particles into the marine environment and the breakdown of existing plastics, providing an immense source of plastic particles.

Plastic debris smothers coral reefs

Plastic debris is smothering and killing coral reefs, with a recent study finding that plastic sits atop almost 92% of the reefs examined. The study, conducted by marine biologist Hudson Pinheiro and 18 other researchers, involved examining trash from 84 reefs across the Atlantic, Pacific, and Indian Oceans. The team found plastic debris, mostly in the form of fishing gear, entangled and stuck in the reefs. This "ghost fishing" equipment continues to trap and kill marine animals even after being discarded.

The impact of plastic on coral reefs is significant and far-reaching. Firstly, plastic debris can cause physical damage to coral tissue, leading to injuries that increase the risk of infection by bacteria present on the plastic. Secondly, plastic debris acts as a vector for pathogens, promoting the spread of diseases between reefs and contributing to higher rates of coral disease. A four-year study found that coral in contact with plastic had an increased risk of four common diseases, with noticeable differences in health between corals with and without plastic.

Additionally, there is evidence that corals may voluntarily ingest plastic due to its chemical additives, further promoting the development of diseases. The presence of microplastics has been shown to impair coral growth, potentially by blocking their digestive tracts and preventing them from digesting their natural diet. The complex 3D structure of coral species also contributes to the transfer and accumulation of microplastics in their tissues.

The problem of plastic pollution in coral reefs is widespread, with plastic debris found in 77 out of 84 reefs surveyed in a Nature study. Plastic pollution was denser in reefs near cities and markets, which is logical given that more people equals more plastic waste. However, plastic debris was also found in some of the most remote and uninhabited reefs, highlighting the far-reaching impact of plastic pollution.

To address this issue, it is essential to reduce plastic consumption, properly recycle plastic waste, and prevent plastic from ending up in the environment. By taking these actions, we can help reduce the pressure on coral reefs and protect their economic, ecological, and cultural value.

Plastic waste carries pathogens that cause coral disease

Plastic waste is a common pollutant in coral reefs, with an estimated 11.1 billion plastic items entangled on coral reefs across the Asia-Pacific region alone. This plastic pollution poses a significant threat to the health of coral reefs, as it has been linked to an increased risk of coral diseases.

One of the primary mechanisms by which plastic waste contributes to coral disease is by carrying and transmitting pathogens. Plastic debris in the ocean can harbour various bacteria, including pathogens that are known to cause diseases in coral reefs. These pathogens can colonize on the plastic surfaces and be transported between reefs, promoting the spread of diseases and increasing the risk of infection among corals.

The presence of plastic waste exacerbates the risk of disease outbreaks in coral reefs. Studies have shown that the likelihood of disease in corals increases significantly when they come into contact with plastic. For example, a survey of over 124,000 corals on 159 reefs in the Asia-Pacific region found that the risk of disease increased from 4% to 89% when corals were entangled with plastic. This drastic increase in disease susceptibility highlights the critical role of plastic waste in facilitating the transmission of pathogens to corals.

The impact of plastic waste on coral disease is not limited to the presence of pathogens. Plastic debris can also cause physical damage to coral tissues, making corals more susceptible to infection by bacteria present on the plastic or in the surrounding environment. Additionally, plastic waste can stress corals through light deprivation, toxin release, and anoxia, further compromising their health and resilience against diseases.

The effects of plastic pollution on coral reefs are complex and multifaceted. While the exact mechanisms by which plastic contributes to coral disease are not yet fully understood, it is clear that plastic waste plays a significant role in exacerbating the vulnerability of coral reefs to diseases. Addressing plastic pollution through proper waste management, reduced plastic consumption, and effective recycling practices is crucial for mitigating the impacts of plastic on coral reefs and preserving the health of these vital ecosystems.

Microplastics impair coral growth

Plastic contamination is one of the most serious environmental issues for oceans. A survey of 150 reefs found plastic to be a common pollutant, with an estimated 11 billion plastic items entangled in coral reefs in the Asia-Pacific region. Marine scientists have discovered that plastic is killing coral reefs, with plastic debris promoting the development of diseases. The risk of disease can be up to 22 times greater on a reef polluted by plastic than on a preserved reef.

Microplastics, or plastic fragments smaller than 5mm, have been a topic of discussion in recent years, with their potential threats to marine ecosystems being actively debated. These small plastics can originate from primary sources, manufactured at microscopic sizes, or derived from the fragmentation of larger plastics. They are composed mainly of polypropylene (24%), low-density polyethylene (21%), polyvinyl chloride (19%), and high-density polyethylene (17%).

Microplastics have been consistently found in all coral reefs studied, associated with the biota, water, and sediments. They pose a serious threat to marine ecosystems and biota, with impacts ranging from individual to ecosystem levels. The effects of microplastics on deep-sea coral reefs have been relatively unexplored until recently. Experiments have been conducted to understand their impact on the growth, feeding, and behaviour of deep-sea coral species, specifically Lophelia pertusa, a major engineer species found in European waters.

The results of these experiments revealed that microplastics significantly reduced skeletal growth rates in Lophelia pertusa. While they did not impact polyp behaviour or prey capture rates, microplastics led to reduced calcification compared to control and in situ conditions. This indicates that microplastics impair coral growth, which is a critical component of reef aggradation and the resilience of cold-water coral reefs.

Further research is needed to fully understand the mechanisms by which microplastics cause adverse effects on coral growth. One hypothesis suggests that ingested microplastics could block the digestive tracts of corals, either leaving them feeling full or preventing the digestion of their natural diet. Additionally, microplastics adhering to coral tissue may impact their ability to capture prey or cause an energy deficit as they expend resources to remove the microplastics.

Plastic debris is denser on reefs near cities

Plastic debris is a significant threat to coral reefs, with a recent study finding that it smothers and kills almost 92% of the reefs examined, including some of the most remote and uninhabited ones. The study, conducted by marine biologist Hudson Pinheiro and 18 other researchers, involved examining trash from 84 reefs across the Atlantic, Pacific, and Indian Oceans. The results revealed that plastic debris, primarily fishing gear such as ropes, long lines, and nets, was present on the majority of the reefs, highlighting the urgent need to address this issue.

The impact of plastic on coral reefs is not limited to physical smothering but also extends to the promotion of disease development. Research suggests that plastic debris can cause physical damage to coral tissue, making corals more susceptible to infections by bacteria and pathogens present on the plastic. Additionally, corals may be attracted to the taste of plastic due to chemical additives, leading to the ingestion of plastic and further increasing the risk of disease.

The density of plastic debris on reefs is influenced by various factors, including proximity to human populations and waste management practices. Reefs located near cities and markets tend to have higher levels of plastic pollution due to increased human activity and waste generation. This is particularly prevalent in low and middle-income countries, such as Brazil, the Philippines, and Comoros, where limited resources for waste management and the use of better fishing gear contribute to higher levels of plastic pollution in the ocean.

Furthermore, the continuous production and use of plastic, coupled with its resistant nature, result in a constant flow of plastic particles into marine environments. Plastic can break down into microplastics and nanoplastics, which have been consistently found in the biota, water, and sediments of coral reefs studied. The impact of these microplastics on coral reefs and other reef organisms is not yet fully understood, but their presence underscores the importance of reducing plastic consumption and improving waste management practices to mitigate their potential ecological effects.

To address the issue of plastic pollution in coral reefs, it is essential to implement regulations that reduce single-use plastic and promote proper waste management and recycling practices. Additionally, there is a need to work closely with communities dependent on fishing to find alternative, biodegradable materials for fishing gear and other products, reducing the amount of plastic that reaches and harms coral reefs.

Plastic fishing gear is a major contributor to coral reef pollution

Plastic pollution is killing coral reefs. A survey of 150 reefs found that plastic was a common pollutant. It is estimated that over 11 billion plastic items could be entangled in coral reefs in the Asia-Pacific region, which is home to over half of the world's coral reefs. Millions of tons of plastic waste end up in the ocean every year, and the trash remains there. Marine scientists have discovered that plastic is killing coral reefs.

Plastic fishing gear is a major contributor to this pollution. Abandoned fishing gear is a major component of the litter on coral reefs. This gear is composed of nets, ropes, and lines made of non-biodegradable plastics. The lost fishing gear is causing tissue loss and fragmentation in reef corals. Most of the lost fishing gear is made of non-biodegradable plastics that may sink to the sea floor or drift around in currents. It may remain unnoticed until it shows up on coral reefs, beaches, and other coastal habitats.

Greenpeace calls for global action over nets, lines, and traps that are deadly for marine life. More than 640,000 tons of nets, lines, pots, and traps used in commercial fishing are dumped and discarded in the sea every year. This gear is designed to catch and kill, and once lost in the marine environment, it can continue to fish, in addition to smothering reefs, trapping animals, and posing a navigational risk to vessels.

Ghost gear, or abandoned fishing gear, is estimated to make up 10% of ocean plastic pollution but forms the majority of large plastic littering the waters. One study found that as much as 70% (by weight) of macroplastics (in excess of 20 cm) found floating on the ocean surface was fishing-related. Another expedition to the South Pacific found an estimated 18 tons of plastic debris on a 2.5 km stretch of beach on the uninhabited Henderson Island, with an accumulation rate of several thousand pieces per day.

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