Global map of ecological risk to sea life from ocean plastic

The highest-risk areas are not always the 'garbage-patches' where plastics visibly pile up, report scientists from Tulane University, USA, and partners.

The highest-risk areas are often where plastics overlap with dense marine life and pollutants.

Even waters with relatively modest plastic levels can face severe ecological threats, they say.

Their analysis shows high-risk zones to include the mid-latitude North Pacific and North Atlantic oceans, parts of the North Indian Ocean and coastal East Asia.

The assessment charts worldwide 'ecological risk hotspots' by evaluating four major pathways of harm for marine life - ingestion, entanglement, transport of toxic pollutants and the leaching of harmful chemicals as plastics break down.

The team has integrated global models of ocean plastics, marine species distribution and pollutant levels to create a framework for assessing ecological threats.

Nutrient-rich waters with abundant marine life appear to drive risk in some cases, even when plastic levels are not the highest.

They have also classified coastal areas near busy fishing grounds as particularly vulnerable to entanglement hazards from 'ghost gear' - abandoned fishing gear in the water, such as gillnets, traps, fishing lines and trawl nets.

The study also identifies plastics' role as a 'conveyor belt' for pollutants, such as the neurotoxic methylmercury and 'forever chemicals' also known as PFAS -  two contaminants that can build up in marine food webs and threaten human health.

The team reports that elevated risks are where contaminated plastics are most likely to be ingested by marine organisms.