Plastic risk maps reveal dangerous hotspots for ocean animals

The ocean is not evenly risky for wildlife. Plastic can do outsized damage in places that do not look choked with trash at the surface.

A new global assessment shows that danger spikes where plastic overlaps with rich marine life and chemical pollution. The researchers tracked four distinct ways plastics hurt animals, from eating and entanglement to acting as carriers and leaching chemicals.

Why plastic risk maps matter

The research team, led by Yanxu Zhang at Tulane University School of Science and Engineering (SSE), built a global picture of ecological risk rather than a count of floating bottles. 

Biomass is the total mass of living organisms in a given area. The researchers combined plastic models with maps of animal biomass to show where contact is most likely and most harmful.

The study was not only focused on where debris drifts, but also on how risk changes for animals of different body sizes and habitats.

A 2020 analysis estimated that 19 to 23 million metric tons of plastic waste entered aquatic ecosystems in 2016. That is a throughput problem, which means risk will keep spreading unless inputs drop.

How plastic hurts animals

Animals eat plastic, become entangled in it, ingest pollutants that cling to it, and absorb chemicals that leach from it. This study charts each of these pathways on a global scale.

The team defines epipelagic species as those living near the surface, roughly the top 650 feet. Mesopelagic species live between about 650 and 3,300 feet.

It is important to distinguish between these zones because plastic concentrations and animal densities do not line up in simple ways.

“Plastic pollution in the ocean is widely recognized as a global concern, but the ecological risks it poses remain poorly understood. We wanted to fill this knowledge gap by systematically assessing how plastics interact with marine life and ecosystems through multiple risk pathways,” said Zhang.

Plastic risk maps reveal hotspots

Hotspots show up in the mid-latitude North Pacific and North Atlantic, parts of the North Indian Ocean, and coastal East Asia. Those areas have abundant wildlife or heavy fishing activity, sometimes both.

The patterns flip some expectations. Subtropical “garbage patches” do not always overlap with the highest animal biomass, so visible trash is not a reliable proxy for harm.

“By mapping the global distribution of plastic related ecological risks, we provide a scientific foundation to guide ocean cleanup priorities and policymaking,” said Zhang.

“This work comes at a crucial moment, as the world is negotiating a global plastic treaty, and we hope our results can help target interventions where they will have the greatest impact.”

Plastics carry dangerous chemicals

Some plastics act like tiny rafts for pollutants. The study highlights PFOS, a perfluoroalkyl substance, and methylmercury, a form of mercury that builds up in food webs. Both can be carried long distances when they stick to plastic.

Methylmercury is a powerful neurotoxin, and exposure at high levels harms the brain and nervous system. Perfluoroalkyl substances belong to a group known as PFAS, chemicals that persist in the environment and can accumulate in people.

When plastics drift from polluted coasts into productive offshore waters, animals face a double hit, ingestion plus contamination delivered together. The map marks this conveyor effect most clearly in the North Pacific and North Atlantic, and in parts of the Indian Ocean.

Fishing gear traps animals

Entanglement risk peaks along busy coasts and on active fishing grounds. Lost or abandoned nets, lines, and traps, widely called “ghost gear,” pose a serious hazard to large fish, seabirds, turtles, and marine mammals.

The United Nations Food and Agriculture Organization has documented these impacts and identified practical remedies in a landmark report. The new map mirrors that evidence, with elevated entanglement risk in the Sea of Okhotsk, the Yellow and East China seas, parts of Southeast Asia, and other busy coastal areas.

Coastal risk dominates because animals and gear are in the same crowded places. Even short foraging trips can intersect with debris fields near ports and fishing grounds.

What the future looks like

The team projected risks under several waste scenarios. Without stronger action, global ingestion risk climbs to more than three times today’s level by 2060.

Cleaner scenarios that cut plastic use and improve waste management reduce several risks, including open ocean entanglement. Gains are not uniform, since rising emissions from some regions can offset progress elsewhere.

Those tradeoffs argue for coordinated policy. Regional success helps, but global cuts in mismanaged waste matter most for long term risk.

Plastic risk maps guide policy

Risk maps help target effort where it counts. The results point to mid-latitude belts, parts of the northern Indian Ocean, and key Asian coasts as priorities for prevention and rescue.

Technology can help, yet it is not a free pass. Recent research weighing large-scale cleanup of the Great Pacific Garbage Patch (GPGP) flagged ecological side effects and costs that managers must account for.

Policymakers can use the risk maps to link immediate actions – like retrieving ghost gear and adopting safer fishing gear – with upstream measures that curb plastic at its source. This combined strategy reflects both the science and the realities at sea.

The study is published in the journal Nature Sustainability.

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