Friday, January 21

The oceans add a new (and shocking) community: islands of plastics are becoming home to coastal species

On May 13, 2020, the locals of southern Oregon found a curious picture on their coast, on the shores of the Pacific: a beached barge, dirty, dumpy, shaken by the waves and with the paint peeling and eaten by the sun. The find would not have greater significance if it were not for the origin of the ship. Like many other boats and boats, it was part of the debris that it generated the gigantic tsunami that struck eastern Japan in 2011.

To make matters worse, the Oregon boat was not empty. On the contrary. On board the biologists found a dozen species of invertebrates, living, active specimens, all representative of the northwestern Pacific Ocean coast, like mussel Cuprous muscle .

The discovery of Oregon –collected in a detailed study just published Nature Communications– is far from being a mere curiosity; It responds, in fact, to a phenomenon that is attracting more and more attention from biologists: how the plastic waste that drifts through the oceans is becoming improvised ships for coastal species, a kind of strong and robust ocean liners that allow them crossing distances that decades ago, when they depended on branches, seeds or algae, all biodegradable, were unapproachable.

Not only that. Plastic is increasingly present in the oceans. By 2050, according to the researchers, the total generation could be at 25 billion metric tons.

Great “boats” to travel thousands of kilometers

As the study authors themselves detail, floating plastic debris, a result of pollution, is “sustaining a new community on the sea surface. composed of coastal and oceanic species”. With a poetic sensibility and a sports metaphor, the experts even have a name for this kind of trip aboard rubble: “Rafting in the ocean”. Localized life in waste like the Oregon boat is called a “neo-pelagic community.”

“The presumed ability of coastal species to survive ocean transits has been a fundamental principle of island biogeography and is believed to explain the presence of species derived from the continent on oceanic islands,” the researchers reflect in their article on Nature, and warn: “The biogeographic barriers imposed by oceans and continents are rapidly becoming obsolete, socially, economically and now ecologically”.

The tsunami de 2011 It has allowed biologists to understand how much the phenomenon is worth keeping an eye on. “Hundreds of Japanese coastal marine species were found alive in the debris that landed on the Pacific shores of North America and the Hawaiian Islands, having traveled more than 6,000 km across the Pacific Ocean, the largest ocean rafting event known in scientific literature to date ”, they point out. The organisms not only survived and grew, some even went so far as to reproduce in the ocean.

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“The discovery showed that anthropogenic debris, which was largely made up of floating plastics, provided long-lasting and habitable rafts. They exceeded our expectations for the survival of coastal species in the sea ”, experts abound.

The first consequence is that the open ocean ceases to act, in a way, as the great “physical and biological barrier” for the dispersal of species, which represents “a paradigm shift in our understanding of marine biogeography”. Another is the existence of “Self-sufficient coastal communities on the high seas” beyond the neuston, organisms prepared to survive on their own in the surface layer of water, such as copepods.

Someone thought that using a giant net to collect plastic from the sea was a good idea, but no: they are sweeping life from the ocean

The phenomenon described in Nature has another important implication: To what extent can it favor the dispersal of invasive species? “Understanding the ecology and biogeography of neopelagic communities in floating plastics will provide essential information on the role of plastics as vectors of non-native species,” says the article by Nature-. The colonization of plastic debris in the sea by coastal species suggests that the continued expansion of the plastifera creates a new source of non-native species in the high seas. […]. As a result, rafting events that were rare in the past could alter ocean ecosystems and change the dynamics of invasion on a global scale. ”

It is not a new concern. About the risk that plastic waste ends up facilitating the dispersal of invasive species already warned months ago, for example, researchers from the University of Florida in a study published in Scientific Reports.

Images | ARC Centre of Excellence for Coral Reef Studies (Flickr), Jennyvids (Flickr)