Scientists have discovered microplastic particles thousands of meters below the ocean surface, in isolated ecosystems where sunlight does not reach.
This reaffirms that plastic pollution is no longer confined to the surface or beaches, but has extended to the farthest and deepest places on Earth.
It is estimated that more than 11 million tons of plastic enter the oceans annually. Over time, this large plastic debris breaks down into very small particles known as microplastics, which are transported by ocean currents to various marine environments, thus threatening marine life and entering the human food chain.
But despite previous studies that have documented plastic pollution in surface and coastal waters, the impact of this pollution on deep-sea habitats, especially hydrothermal vents, is still not sufficiently known.
In the world’s first comparative study of its kind, scientists from South Korea revealed how microplastic particles accumulate in organisms living in hydrothermal vents on the ocean floor, in two different oceans: the North Fiji Basin in the southwest Pacific Ocean, and the Central Indian Range in the Indian Ocean, at depths of more than 2,000 meters below the water surface.
By analyzing snails and sea snakes collected from these openings, scientists found plastic particles in 92% of all the organisms they examined, with an average of 3.42 particles per organism.
Polystyrene – used in consumer products and packaging materials – was the most common type among the molecules discovered.
"Plastic pollution has now spread even to deep-sea hydrothermal vent systems, which were once considered among the most isolated environments on Earth," said Dr. Se-Joo Kim, one of the authors of the study published in the journal "Water Research."
The study showed that the way these organisms are fed plays a major role in determining where plastic particles accumulate in their bodies.
In snails that feed on the microbial layers covering the seabed, the molecules are concentrated mainly in the digestive organs, while in filter-feeding marine cichlids, the molecules are distributed relatively evenly throughout all tissues.
The study revealed that animals collected from the Indian Ocean contained significantly higher concentrations of plastic particles compared to those from the southwest Pacific Ocean, with the proportion in Indian Ocean organisms being 15 times higher after adjusting the results according to body weight.
The study definitively proves that plastic pollution generated on the ocean surface can travel thousands of meters towards the bottom, reaching one of the most remote and extreme marine ecosystems on Earth.
Dr. Kim concluded: "Our results provide important scientific evidence for developing deep-water environmental monitoring systems and future protection policies."
