Five things you need to know about ocean plastics

Published 6 June 2026 · science

Once plastics are released into the marine environment, large pieces choke wildlife and disturb fragile habitats like coral reefs before breaking down into toxic microplastics

Once plastics are released into the marine environment, large pieces choke wildlife and disturb fragile habitats like coral reefs before breaking down into toxic microplastics that poison the food chain. Even when they have fully disintegrated physically, their chemical bonds remain and the impacts persist. Today, more than 4,000 marine species are known to be affected by plastics, according to the World Ocean Assessment, the only analysis of the world’s ocean across the three pillars – environmental, economic and social – of sustainable development. Dr Ian Butler, an editor of the 1,600-page report that includes contributions from over 650 experts, said the whole marine system is being affected: “it’s their feeding, their metabolism, their immune function, their growth and reproduction. It weakens and kills them, and changes populations.” Ahead of World Ocean Day on June 8, here are five things you need to know about ocean plastics 1. Ocean plastic pollution is still rising The amount of plastic in the ocean is still rising, driven by mismanaged waste, littering, microplastic abrasion and marine activities. Plastic waste emissions are estimated at 52.1 million metric tonnes per year. There are also different regional patterns: littering is described as the largest source of pollution in the Global North, while uncollected waste dominates in the Global South.

These ‘leakages’ are what causes the ocean so much damage. “What our eyes see is the tip of the iceberg,” Dr. Butler warned. Floating and beach macro- and microplastics account for only three to four per cent of total ocean plastic, meaning much of the problem is dispersed, submerged, fragmented or otherwise hard to recover. Unsplash/Naja Bertolt Jensen 2. The smallest plastics are the biggest unknown Once plastic reaches the ocean, it is not just confined to beaches or floating garbage patches - microplastics have been found from surface waters to the deepest depths of the ocean. It is estimated that there are some 24.4 trillion microplastic pieces in the world’s upper oceans. Microplastics are small plastic pieces less than five millimetres long, often breaking down from larger plastic items, and can cause alterations to the immune system, inflammation, decreased growth rates, and energy imbalance. However, our understanding of nanoplastics and their long-term biological effects is still very limited – the less visible the plastic becomes, the harder it is to detect, monitor, remove and assess for risk. At the same time, it becomes easier for the plastic to penetrate natural biological barriers such as cell membranes. The concentration of these tiny plastics also “magnifies through the food chain – from the smallest creatures, who get eaten, and then it accumulates higher and higher up,” Dr Butler said.