Plastic Pollution's Impact On Coral Reefs: What's The Truth?

Plastic pollution is a pressing issue that poses a grave threat to coral reefs, which are among the most biodiverse and endangered habitats on Earth. The presence of plastic waste in oceans has been linked to an increased risk of disease in corals, with plastic acting as a vector for pathogens. Plastic debris can block sunlight, cause physical abrasion, and create low-oxygen conditions, all of which contribute to the spread of harmful pathogens. Additionally, the chemicals used in plastic production can leach out, impacting the health of oxygen-producing bacteria in the ocean. The ingestion of microplastics by corals can lead to a false sense of fullness, reducing their food intake and affecting their growth and survival. The impact of plastic pollution on coral reefs underscores the urgent need for plastic waste reduction and improved waste management practices to protect these valuable ecosystems.

Plastic waste makes corals more vulnerable to potentially fatal diseases

Coral reefs are incredibly susceptible to plastic pollution. A four-year study found that plastic waste is killing coral reefs in the Pacific Ocean, from Thailand to Australia. Billions of plastic items were found entangled in the reefs, with branching coral being more prone to snagging plastic.

Plastic waste can promote microbial colonisation by pathogens, which cause disease outbreaks in the ocean. The likelihood of disease increases from 4% to 89% when corals are in contact with plastic. This is due to several factors. Firstly, plastic abrades corals, creating openings that allow infections to start. Secondly, plastic can block sunlight from reaching the coral, causing further stress. Finally, plastic debris can release toxins and cause anoxia, giving pathogens a foothold for invasion.

The impact of plastic waste on coral reefs is far-reaching. Structurally complex corals are eight times more likely to be affected by plastic, which suggests that microhabitats for reef-associated organisms and valuable fisheries will be disproportionately impacted. The Asia-Pacific region, home to over half of the world's coral reefs, is estimated to have over 11 billion plastic items entangled in its coral reefs. This number is projected to increase by 40% by 2025.

The effects of plastic pollution on coral reefs are devastating, and the urgent need for protection against the damaging effects of plastic waste is evident.

Plastic breaks down into microplastics that enter our food chain

Plastic pollution is a pressing issue that is causing coral reefs worldwide to get sick and die. A four-year study in the Pacific Ocean found that plastic waste such as bags, bottles, diapers, and wrappers is causing extensive damage to reefs from Thailand to Australia. The plastic clings to the coral, blocking sunlight and providing a foothold for pathogens, increasing the likelihood of disease from 4% to 89% when corals are in contact with plastic.

Plastic breaks down into microplastics, which are now found everywhere in the environment, including in the human food chain. Microplastics are defined as small pieces of plastic less than five millimeters in size. They can be pre-production plastic pellets or particles derived from various products such as electronic equipment, packaging, bottles, vehicle parts, paints, synthetic textiles, and fishing gear, among others.

Microplastics can enter the human food chain through the consumption of contaminated food and drinks, including seafood, plant and animal-origin foods, and food additives. They can also enter through the use of plastic food packaging and personal care products. Microplastics have been found in honey, sugar, beer, sea salt, bottled water, and even in placentas and human stool samples.

The presence of microplastics in the human food chain poses a potential threat to human health. They can accumulate in the cells and tissues of living organisms, leading to adverse health effects such as gastrointestinal disorders, immune problems, respiratory issues, cancer, infertility, and alterations in chromosomes. They can also carry other toxic chemicals and microorganisms, including harmful bacteria and persistent organic pollutants such as polychlorinated biphenyls (PCBs), heavy metals, antibiotics, and pesticides.

The impact of microplastics on human health is an area of ongoing research, and the specific mechanisms by which they cause harm are still being investigated. However, the widespread presence of microplastics in the environment and the food chain underscores the importance of further study and the need for strict regulations to control plastic use and improve waste management practices.

Plastic increases the chance of coral disease

Plastic pollution is a major threat to coral reefs, and it significantly increases the likelihood of disease in corals. The presence of plastic waste in coral reefs has been associated with a substantial increase in the risk of disease, rising from 4% to 89% when corals come into contact with plastic. This drastic increase in disease probability highlights the detrimental impact of plastic on the health of coral reefs.

Plastic debris harms coral health through several mechanisms. Firstly, plastic can physically abrade and damage the coral, creating openings that allow pathogens to infect the coral more easily. This damage to the coral's surface acts as an invitation for harmful microorganisms to invade. Secondly, plastic can block sunlight and oxygen from reaching the coral, causing stress and making the coral more susceptible to infection. Deprivation of light and oxygen are essential factors that contribute to the increased disease risk.

Additionally, plastic debris provides an ideal habitat for microbes, including pathogens, to colonize and grow. Plastic items, such as bottle caps and toothbrushes, made from materials like polypropylene, have been found to harbor significant bacterial growth. This colonization of plastics by bacteria is linked to the devastating group of coral diseases known as white syndromes, which are spread by bacteria and cause tissue loss in corals. The presence of plastic, therefore, increases the risk of disease transmission to the corals.

The impact of plastic on coral disease is further exacerbated by the fact that once coral tissue loss occurs due to disease, it is irreversible. The disease can spread throughout the coral, similar to how gangrene can affect the human body. This irreversible nature of coral tissue loss underscores the severity of the problem posed by plastic pollution in coral reefs.

To protect coral reefs, it is crucial to reduce plastic waste and improve waste management practices. By minimizing the amount of plastic entering ocean ecosystems, we can reduce the detrimental effects of plastic on coral health and lower the likelihood of disease outbreaks in these valuable ecosystems.

Plastic promotes the growth of harmful pathogens

Coral reefs are already susceptible to disease due to unusually warm waters. However, plastic pollution is making matters worse. A study published in the journal Science found that the likelihood of disease in corals increases from 4% to 89% when corals are in contact with plastic.

Secondly, plastic can block sunlight from reaching the coral, causing stress and making the coral more susceptible to infection. Deprivation of light, along with oxygen deprivation and toxin release caused by plastic debris, gives pathogens a foothold for invasion.

In addition, plastic itself may be a carrier of pathogens. Plastic items, such as bottle caps and toothbrushes, have been found to become heavily inhabited by bacteria. This is associated with a group of coral diseases known as white syndromes, which cause parts of corals to die, leaving a white band of dead tissue.

The presence of plastic increases the susceptibility of corals to disease and may contribute to the devastation of the world's reefs, many of which have already been weakened by climate change-induced bleaching events.

Complex corals are particularly at risk

Research has shown that some species of coral are more likely to be affected by plastic pollution than others. Structurally complex corals, such as staghorn coral and other branching forms, are eight times more likely to become entangled in plastics. This is a significant problem for the wider marine ecosystem, as these types of coral, with their intricate and delicate structures, provide hiding places for juvenile fish and are usually ecologically important environments, especially as nursery habitats.

The more spikey the coral species, the more likely they are to snag plastic. This is due to the abrasion (tissue scraping) caused by plastic particles, which can wound the corals. These injuries may then become infected by fungi or bacteria, killing some cells or even the entire coral.

The abrasion caused by plastic can also create cuts and openings in the coral's surface, essentially tearing open the skin of the coral. This can allow infections to enter from anywhere, leaving the coral very vulnerable to disease. Furthermore, when coral loses tissue, it grows back exceptionally slowly, giving pathogens a greater chance to infect the coral.

The risk of entanglement with plastic is also a problem for the corals themselves. When plastic settles on coral, it creates low-light and low-oxygen conditions, which are ideal for microbes that cause diseases such as black band disease to flourish. This can result in complete tissue degradation.

The ingestion of plastic by corals is also a serious issue. Research has found that corals are ingesting plastic and, in some cases, actively seeking it out as a food source. It is thought that the chemical compounds that plastics are made of make them appealing to corals. This relationship needs to be investigated further, as if these plastics are carrying contaminants or disease, this would be a very toxic relationship.

To protect complex corals and other coral species from the harmful effects of plastic pollution, it is crucial to reduce plastic production and plastic waste. Individuals can play a role by reducing their plastic usage, reusing plastics, and recycling. Supporting large-scale projects like the Ocean Clean Up and plastic removal initiatives is also important. Additionally, investing in chemical removal technologies to eliminate harmful leachate from the oceans is necessary to make them a habitable place for marine life to thrive.

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