Marine plastic: a new and growing threat to coral reefs

UNEP 5 Mar 18;

New evidence is emerging that shows that the human population’s obsession with all things plastic is poisoning one of the world’s natural wonders: coral reefs.

Much more than simply an object of beauty, coral reefs are living, breathing ecosystems, teeming with life. Although they occupy less than 0.1 per cent of the world's ocean surface, they provide an essential home for 25 per cent of all marine life; they are also vital for protecting coastal communities, acting as natural barriers from cyclones and rising seas; and 275 million people depend directly on them for their food and livelihoods.

Yet coral reefs are under attack on a number of fronts. In the past 30 years, we have lost up to 50 per cent of the world’s corals from the effects of warming sea temperatures due to climate change, overfishing, and a range of land-based activities. However, a major new study has revealed they are also under siege from plastic.

Each year, it is estimated that more than 8 million tonnes of plastic are ending up in the oceans – the equivalent of emptying a garbage truck of plastic every minute. We are producing 20 times more plastic today than in the 1960s. If we continue the current rate of plastic usage, we will have produced another 33 billion tonnes of plastic by 2050; a large portion of which will end up in oceans, where it will remain for centuries.

In a survey of 159 coral reefs in the Asia–Pacific region, published in Science this year, researchers estimate there to be a staggering 11.1 billion plastic items entangled in the corals. This number is projected to increase by a further 40 per cent in just the next seven years.

Of the 124,000 individual reef-building corals that were assessed, 89 per cent of those smothered in plastic were facing the threat of disease compared with only 4 per cent in corals free from plastic. The plastic debris starves corals of vital oxygen and light, and releases toxins enabling bacteria and viruses to invade.

In another study published in the journal Marine Pollution Bulletin in October 2017, scientists recorded a worrying development in the ingestion of plastic by marine wildlife. There is myriad evidence of marine wildlife fatally mistaking plastic debris, particularly microplastics, for food.

However, researchers observed coral were not simply mistaking the small plastic particles for food; they were displaying a deliberate feeding response when the plastic floated by. In other words, there is something dangerously tasty about the chemical compounds in plastic, a development the researchers warned needs to be better understood to prevent further contamination and disease.

The International Coral Reef Initiative (ICRI) has declared 2018 the International Year of the Reef. UN Environment together with partner organizations is working to raise awareness about the value and importance of coral reefs and threats to their sustainability, and to motivate people to take action to protect them.

#BeatPlasticPollution is the theme of World Environment Day 2018. Join the movement to break up with single-use plastic.