The effect is a bit like what we know from sunken ships: after a while, sea creatures settle on the man-made scrap.
US researchers have now demonstrated in a study that new habitats for a number of species that are not normally at home in the open sea have emerged in the plastic waste floating in the Pacific: in the waste of the northern Pacific Ocean, between California and Hawaii, they detected a total of 37 invertebrate species, as they describe in an article this week in the journal Nature Ecology and Evolution. Overall, they found coastal creatures in more than two-thirds of the debris from the massive garbage patch known as the "Great Pacific Garbage Patch."
There have been repeated reports for a few years that animals are settling in the garbage of the oceans. The research group led by Linsey Haram from the Smithsonian Environmental Research Center in Edgewater has now investigated this effect in more detail and has shown that the species are able to survive on the floating debris for a long time and in some cases even reproduce. The animals are therefore permanently conquering the habitat garbage in the sea.
Like on rafts, the organisms drift through the oceans that they would otherwise never be able to colonize. They usually require substrate or - as in the case of anemones - a firm footing such as sediment or rock. Food is also usually scarce in open water.
Creatures identified by Haram and her team on ocean debris included invertebrate shellfish such as small crabs, molluscs such as anemones, and moss-like creatures called bryozoans. According to the researchers, the original home of these animals was very distant coastal regions, for example in Japan. In their new environment on the ocean litter, they fed on slime made from bacteria and algae that they found on the plastic waste.
Docked to plastic bottles, containers and other civilization waste, the organisms managed to open up new habitats for themselves in this way.
The scientists observed a similar effect after the tsunami in Japan in March 2011, as the study states, among other things: At that time, vast amounts of debris and sediment were washed into the sea and carried with the sea currents over long stretches of the ocean. As a result, a total of 381 coastal animal species from Japan were found in North America and Hawaii between 2012 and 2017.
The migration of living beings in the wake of civilization is also nothing new. They are known from plants on land, insects and even mammals, such as the raccoon, which has now also settled in Germany. Such species travel to new places in a wide variety of ways – in ships or airplanes, on car tires or they are deliberately transported by people. Such arrivals can be problematic when they displace native species and disrupt ecosystems.
How the distribution of coastal animals on the ocean affects the ecosystems there has not yet been researched. In general, however, the garbage in the sea is a massive problem - not only because microplastics get into the food chain. Many animals also die because they get caught in or eat the refuse. The "Great Pacific Garbage Patch" is notorious for its estimated size alone: it is reportedly about four and a half times the size of Germany.
Sources: "Nature Ecology and Evolution", "Wissenschaft.de" / with material from AFP