The small filtering animals that live in the oceans absorb tiny pieces of plastic and spew them out in granules. The latter then sink to the ocean floor.
Observations of such creatures, known as appendiculars, show that they are capable of "scattering" huge amounts of microplastics from the upper layers of the ocean to the depths. Perhaps they will help answer the question that has long tormented scientists: why is there much less plastic floating in the ocean than expected?
Removing plastic from surface water may sound like a good idea, but the reality may be different. This means plastic is a much bigger threat, says Kakani Katija of the Monterey Bay Aquarium Research Institute. “It can have a detrimental effect on creatures that live in the depths of the ocean,” she said.
By the way, there really is a reason for such concern: the pollutants banned decades ago were found even in the Mariana Trench.
Moreover, microplastics may well affect people, says scientist Anela Choy. We eat a lot of sea creatures that live on the seabed. And pollution of the ocean by microplastics, by the way, has already jeopardized the global oyster harvest.
While such a thing as the Great Pacific Garbage Patch conjures up images of a floating garbage island, most of the plastic in the world's oceans is made up of tiny pieces that remain invisible to the human eye.
To find out what actually happens to the plastic, researchers began studying the appendiculars, focusing on the giant Bathochordaeus stygius. The length of creatures resembling tadpoles does not exceed a few centimeters, but the mucus of the house they secrete can be up to one meter in diameter.
Previous studies by Cathius have already shown that such animals filter huge amounts of seawater every year. “They are incredibly important organisms in the middle waters,” she notes.
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This time, specialists used remote-controlled vehicles to spray tiny plastic balls near individual giant appendiculars. The scientists wanted to find out what would happen. All observations took place at a depth of 200-400 meters.
Some plastic balls adhered to the slimy houses of the appendiculars, which they regularly discard. Other pellets were swallowed and then "integrated" into the fecal lumps. Both the house and the result of the dinner are subsequently submerged on the seabed, where all this is then eaten by other animals.
Matthew Cole of the University of Exeter says that these same faecal pellets, containing floating plastic, sink to the bottom more slowly, hence the likelihood that they will be eaten on the way down.
“In other words, there is a chance that the plastic will again be eaten by other animals,” he says. So far, only one thing remains unclear: how microplastics affect the body of animals that feed on it.
The research results are published in the scientific journal Science Advances.
