Since the Japanese tsunami of 2011, scientists suspect that coastal species may be able to surf plastic waste to find themselves living in the open sea. Thus breaking down biogeographical barriers that researchers thought insurmountable. The dawn, perhaps, of significant ecological changes in the marine environment.
In the North Pacific, somewhere between Hawaii and California, there is a region that reminds us of our excesses. Bags plastics, bottles, packaging, nets. A gigantic vortex of waste that English speakers call the Great pacific garbage patch (GPGP). It would cover 1.6 million square kilometers. That is three times the area of France. Almost 80,000 tonnes of plastic waste floating. And we can imagine that this poses a problem. To marine life, in particular. When it ingests or becomes entangled in these abandoned plastics.
But that’s not all. From researchers from the Smithsonian Center for Environmental Research (SERC, United States) today reveal another complication due to plastic waste at sea. They observed that cash coastlines can colonize this waste and end up hundreds of kilometers offshore. Far beyond their range traditional.
Remember that surface currents can form swirls of plastic waste that travels from coasts to more distant regions. There, this waste becomes trapped in rotating currents. They then accumulate in particular on the side of the North Pacific waste vortex. With, on their surface, organisms used to living on the coasts. Scientists speak of neopelagic communities. And they suspected their existence since they had discovered nearly 300 species that have crossed the Pacific on the debris of the tsunami Japanese from 2011.
A new risk for high seas species
This time, the researchers analyzed samples of the roughly 103 tonnes of plastic and other waste collected in 2020 by theOcean Voyages Institute. The organization has set itself the objective of recovering this waste by traveling to the GPGP on board sailboats. Researchers have found many coastal species on this plastic waste. Anemones, hydroids – their distant cousins - and amphipods – those sea fleas that look like shrimp. Species not only alive, but thriving.
A real surprise for scientists who until then considered that no coastal species could survive offshore. Because of habitat limitations and a supposed food desert. But now, plastic seems to provide shelter for these species. Who, one way or another, also manage to find food in the heart of the ocean. Perhaps because plastic also attracts some of the food sources required.
What worries researchers is how much these new species could disrupt an environment that has remained intact for millennia. Some change native also live there. And even on this plastic waste. How will they welcome this unexpected competition? The question could also arise a little further still. After the Japanese tsunami, coastal species native to the country of Sun Levant found themselves, after floating on the high seas for months, if not years, on the coasts of North America.
With on the one hand, the production of plastic which never ceases to climb, and on the other hand, the multiplication of storms violent under the effect of global warming, researchers fear that more and more waste will end up dumped in the seas. Neopelagic communities should therefore only grow. With the risk that this will end up transforming life at sea … and on land!
Colonies of microbes in the oceanic plastisphere
The plastisphere, this new marine ecosystem that thrives on plastic waste, is teeming with microbes and bacteria of all kinds. If it is difficult to predict the effects that this new world will have on the ocean, we can already say that it modifies the development of micro-organisms and may well carry disease.
Article by Delphine Bossy published on 07/02/2013
The most abundant marine debris is plastic waste. Of the 260 million tonnes of plastic produced each year, 10% ends up at sea. Ocean circulation carries waste away from the coast, into ocean gyres where it accumulates and slowly degrades. These areas of accumulation are often called plastic continents Where plastic islands. The notion of macroscopic plastic plaque is misleading, we should rather speak of microscopic plastic soup. Nevertheless, the abundance of material in the ocean led to the proliferation of thousands of bacteria, founding a new ecosystem, the “plastisphere”.
This new ocean habitat raises a number of questions. Will the new environmental conditions favor the development of species to the detriment of others? How does the proliferation of marine life from this plastic waste could it modify the food chain ? When they die, will these organisms dive to the bottom of the ocean or will they be ingested? What impact can the plastisphere have on the ocean? Difficult to answer now, but a team from Woods Hole Oceanographic Institution (WHOI) gives some elements of analysis.
The team studied plastic debris collected from different points of the gyre of the North Atlantic, from microscopic mesh nets. Most of the debris recovered was no larger than a millimeter, but housed a rich microbial life. The results of the analysis, published in the journal Environmental Science & Technology, report more than a thousand different species developed on a single plastic micro-waste.
Plastic in the days of cholera
On a piece of plastic barely the size of a pin, researchers found organisms autotrophs (phytoplankton and bacteria), animals and bacteria that feed on them, and larger predators. They have also identified real symbiotic relationships between some of these organizations. The plastisphere can be seen as a new microbial reef.
Studied using scanning electron microscopy and scanning techniques gene sequencing, bacteria show a different development than those that grow on natural reefs. the plastic degrades less quickly than drink or the feathers they normally live on, and provide some very unusual nutrients. The team shows in particular that microbes are able to degrade plastic. They observed cracks and microscopic pits in the material, which revealed that the bacteria attacked the hydrocarbon chains.
The plastic debris therefore represent a new ecosystem, but could also be a new mode of transport, vector of harmful microbes. On one of the plastics studied, the dominant population belonged to the genus Vibrio, which includes bacteria from cholera and bacteria vectors of gastrointestinal diseases. The WHOI team hopes for the future to be able to identify and sequence all the bacteria that can be found in these environments, in order to develop cultures in the laboratory and study their mode of operation.
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