Coral's Plastic Pollution Plight: Understanding The Impact

Coral reefs are vital ecosystems that support a diverse range of marine life. However, these fragile environments face various threats, including plastic pollution. Plastic waste, such as bags, bottles, fishing gear, and microplastics, is increasingly endangering coral reefs, causing physical damage, spreading diseases, and impairing coral growth. Understanding the impact of plastic pollution on coral reefs is crucial for developing effective conservation strategies to protect these valuable ecosystems.

Plastic debris blocks sunlight from reaching coral

Coral reefs are incredibly important habitats that provide refuge and protection for a diverse range of marine life, including fish, crustaceans, and mollusks. Unfortunately, they are under severe threat from plastic pollution, which is causing

Plastic waste increases the likelihood of coral disease

Coral reefs are already susceptible to disease due to factors such as unusually warm water, overfishing, and climate change. Plastic pollution is an additional stressor that increases the likelihood of coral disease.

A 2018 study published in the journal Science found that the likelihood of disease increases from 4% to 89% when corals are in contact with plastic. This is because plastic can cause physical damage to coral tissue, creating openings that allow pathogens to infect the coral. Plastic can also block sunlight from reaching the coral, further contributing to disease development.

The impact of plastic on coral disease was studied for the first time in eight regions of the Pacific Ocean. Researchers examined the health of more than 124,000 corals on more than 150 reefs and found that plastic debris promoted the development of diseases. The risk of disease was up to 22 times greater on reefs polluted by plastic compared to unpolluted reefs.

Additionally, plastic debris carries bacteria, including some pathogens that cause coral disease, and promotes their spread between reefs, increasing the risk of infection. Another study suggests that corals may voluntarily ingest plastic due to the chemical additives present, which further increases the likelihood of disease.

The impact of plastic on coral disease is a serious concern as it contributes to the degradation of coral reefs, which are already under significant threat from other factors.

Plastic can abrade coral, creating openings for infection

Coral reefs are incredibly important for marine biodiversity, but they are facing a multitude of threats, one of which is plastic pollution. A four-year study by marine scientists examined 159 reefs in the Pacific Ocean, from Thailand to Australia, and found that plastic is killing coral reefs.

Plastic is a well-known threat to the ocean environment, with between 60% and 80% of marine trash being plastic. It is affecting over 800 species, and coral reefs are no exception. The study found that reefs in Australia, Thailand, Indonesia, and Myanmar were heavily contaminated with plastic. It clings to the coral, causing sickness and death.

One of the ways plastic harms coral is by abrasion. Plastic rubs against and tears open the delicate skin of the coral, creating openings that allow infections to start. Drew Harvell, a senior author at Cornell University, explains that "plastics abrade corals, create new openings... They basically tear open the skin of the coral and that can allow an infection from anywhere to start." This abrasion also forces the coral to expend energy on its immune response as it tries to repair itself.

Coral is already susceptible to disease due to unusually warm water and bleaching events caused by climate change and human activities. The presence of plastic compounds these issues, making the coral even more vulnerable to infection. Joleah Lamb, a marine disease ecologist who led the research, compares the impact of plastic on coral to "cutting yourself with a really dirty knife." The pathogens that cause coral diseases may be hitching rides on the plastic pieces, further increasing the risk of infection.

The impact of plastic on coral reefs is a serious issue, and it is important to address it through improved waste management, reduced plastic usage, and other measures to protect these vital ecosystems.

Microplastics impair coral growth

Coral reefs are already susceptible to disease due to unusually warm waters and overfishing. Plastic pollution is an emerging threat to coral reefs, spreading throughout reef food webs and increasing disease transmission and structural damage to reef organisms.

A study by EPA scientists found that long-term exposure to microplastics impaired the growth of two different species of coral. The exact mechanisms that cause these adverse effects are still unknown, but there are a few theories. Firstly, ingested microplastics could block the corals' digestive tracts, leaving them feeling full or preventing digestion of their natural diet. Secondly, microplastics adhering to coral tissue could be preventing them from capturing prey or causing them to waste energy removing the microplastics from their surface.

Another study by Lamb et al. in 2018 found plastic waste on coral reefs to be associated with disease. They found that the likelihood of disease increases from 4% to 89% when corals are in contact with plastic. The risk of disease can be up to 22 times greater on a reef polluted by plastic than on a preserved reef. Four of the most common coral diseases, three of which are associated with rapid coral mortality, are more prevalent on reefs contaminated by plastics.

The more complex and branched the shape of the coral, the more likely it is to retain debris, and therefore be affected. Plastic debris has a direct effect on the development of disease by causing physical damage to coral tissue. By carrying pathogens within and between reefs, plastics promote their spread and increase the risk of infection.

It is important to note that plastic is not the only pollutant affecting coral reefs. A study by Pinheiro and 18 other researchers found that the majority of plastic debris on coral reefs was, in fact, plastic fishing gear such as ropes, long lines, and nets.

Plastic waste is denser on reefs near cities and markets

Marine biologist Hudson Pinheiro and 18 other researchers examined trash from 84 reefs across the Atlantic, Pacific, and Indian Oceans. The study, which was published in Nature, found that plastic debris sits atop almost 92% of the reefs they studied, including some of the most remote and uninhabited ones.

The study also found that plastic pollution was denser on reefs near cities and markets, which is logical as more people equals more plastic waste. However, there was also a significant amount of plastic found in marine protected areas, underwater regions intended for long-term conservation, which was unexpected. This was explained by the fact that these areas are where fish and fishermen are found in relatively higher abundance.

The study also found that the type of plastic waste found on the reefs was predominantly plastic fishing gear, such as ropes, long lines, and nets, rather than plastic bags and bottles, which are also harmful to reefs. This type of fishing gear can get entangled and stuck in the reef, continuing to catch fish even after being discarded or lost, a phenomenon known as "ghost fishing."

The study's findings highlight the urgent need to address plastic pollution and its detrimental impact on coral reefs.

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