MOSCOW, May 27, by Tatyana Pichugina. Scientists warn that plastic cleansing could damage the fragile ecosystem that has developed in hard-to-reach regions of the Pacific Ocean. The fact is that garbage patches have become a haven for many organisms. If you are too diligent in protecting the environment, there is a risk of destroying them — and thereby interrupting the food chain.
New colonists
In the 1990s, large accumulations of garbage were discovered in the Pacific Ocean, mostly plastic — bottles, nets, household items. They fall into the water from the shore, from the mouths of rivers, from passing ships. Oceanic circular currents pick up garbage, carry it away for thousands of kilometers. The tailings form islands and spots in the places where the currents turn. These regions are offshore and difficult to access, but in recent years they have received a lot of attention due to pioneering clean-up projects.
It would seem that cleansing the ocean is a good thing. However, scientists ask not to be too zealous: useful organisms can be removed along with waste. Recent studies have shown that garbage patches have developed peculiar ecosystems and active interference can damage various ocean species. 
In 2011, after the earthquake in Japan, the tsunami reached North America. For several years, debris washed up on the shores. Biologists have counted more than 100 thousand objects, and on them — 381 species of microorganisms of Japanese origin. Even in 2020, plastic objects with attached overseas residents were still found off the coast of America. The fact is incredible: it was previously believed that coastal organisms were not able to live long in the open ocean — due to differences in water salinity, nutrients and temperature. Something must support their existence — some kind of islands, stable spaces.
To test the hypothesis, the scientists decided to study samples from the largest garbage patch in the Pacific Ocean — the eastern one. They were collected in 2018-2019 during the ocean cleaning expedition The Ocean Cleanup. In total, about a hundred plastic objects fell into the hands of scientists, which became home to dozens of taxa of microorganisms — bryozoans, crustaceans, mollusks, cnidarians. Of these, 80 percent are coastal species, including Japanese ones. But to the nearest coast there are thousands of kilometers.
«We were struck by how many shore species turned out to be on relatively small samples,» said study leader Lynsey Haram of the Smithsonian Environmental Research Center in an interview. 
The most amazing thing is that individuals not only survived on garbage islands, but also multiplied, like, for example, anemones. Another curious fact: on some of the wreckage, ocean and coastal animals coexisted, and not always peacefully — traces of eating purple snails by anemones are visible.
Coastal species, accidentally caught in the open ocean, successfully colonized the garbage patch, the scientists concluded. In fact, the plastic floating on the surface helped them expand their habitats. And this can lead to unpredictable consequences.
Neuston Seas
It turned out that the debris is actively populated by free-drifting organisms, which are united by the term «neuston». Unlike fish, they do not control their movement, but move in the near-surface layer due to currents. In stagnant waters form vast areas visible to the naked eye. The largest reservoir of neuston is the Sargasso Sea, named after the algae of the same name.
Neuston is an important part of the ocean's food chain; albatrosses and turtles feed on it. As it travels with the ocean currents, it accumulates at the turning points like debris. As it turned out, these microorganisms also live quite successfully on plastic, which means that they can suffer during ocean cleanup.
Non-commercial project The Ocean Cleanup removes plastic using two ships that pull a giant net and shovel debris. Then it is lifted and sorted. This approach worries scientists, so they try to get to the very center of the garbage patch. The concentration of plastic there is an order of magnitude higher than in other parts of the ocean: it is estimated that up to 80 thousand tons.
In a joint publication with ecologists, experts listed the most common species that inhabit the garbage: porpit hydroids, water striders, holobates, pteropods, isopods. In their opinion, removing waste in large nets can also scoop up a critical amount of neuston, so the benefits and harms of such a method should be well weighed.
According to scientists from the UK and the USA, neuston has about twenty functions that are useful for the environment and people. For example, Sargassum seaweed is cultivated in Asia as a food product. The fry of some commercial fish live among the neuston. There are microorganisms that help break down the debris floating in the ocean. Since neuston accumulates in the same places as plastic waste, cleaning up will inevitably lead to its capture.
In a new article published in the journal PLOS Biology, the authors, led by Rebecca Helm from Georgetown University in the USA, note that garbage islands can be neuston concentrators are no worse than the Sargasso Sea and can play the same important role for ecosystems. Scientists took a trip through the Great Pacific Garbage Patch, following simulated pathways of increased plastic concentrations, and found an abundance of neuston. Moreover, for three of the five groups there was a direct relationship: the more plastic, the more microorganisms (sailfish Velella sp, hydroids Porpita sp, gastropods Janthina sp). It turns out that the activity of cleaning up the ocean from debris can disrupt the original habitat, important for other marine animals.