Last month saw the second annual symposium of the Polymers & Oceans Scientific Research Group. Created in 2019 under the direction of the French National Council for Scientific Research (CNRS), in partnership with the French Institute for Marine Research (Ifremer) and the National Health and Environment Agency (ANSES), it brings together 215 researchers from 45 different French-speaking laboratories. Its members, whose aim is to carry out a comprehensive and multidisciplinary study of the evolution and impacts of plastics in aquatic environments, have just presented their latest results, focusing in particular on the discovery of what could be called a “plastisphere”.
Discovery of a new form of life on plastic waste
While the detrimental impacts of macroplastics on marine ecosystems are now well-known, research into the consequences of the presence of smaller marine litter – micro and nanoplastics – is just beginning. This is the aspect on which the researchers of the Polymers & Oceans Group have decided to focus.
Among the findings announced at this latest conference, the scientists described in particular the development of microbial life on the surface of micro and nanoplastics. These plastics, which are composed of a wide variety of chemicals, appear in fact to constitute an ideal habitat for new fungi, bacteria, viruses and invertebrates. More than a thousand species are thought to have already been identified on microplastics floating in the Pacific and Atlantic. Their great variety and rapid proliferation has even led experts to give this group of microorganisms the name of “plastisphere”, echoing the biosphere which designates living things on the Earth’s surface.
Plastic waste: rafts for microorganisms
Besides being varied, these species are spreading rapidly to the four corners of the globe. Since it is non-degrading, plastic waste circulates over long distances, following ocean currents, and becomes what are effectively rafts for bacteria and other viruses, thus facilitating their dissemination and development all over the world. More than 200 invertebrate species were transported from the Japanese coasts to the American west coast, for example, following the 2011 tsunami. Meanwhile, by moving from their region of origin to far-away places, these invasive microorganisms are liable to disrupt fragile balances in local ecosystems.
Invasive species impacting all ecosystems
The dangerous nature of these microplastics, which are already toxic in themselves, both by their physical presence and the additives they contain, is therefore increased by the microorganisms they concentrate and transport throughout the ocean. It has been proven that certain bacteria can poison marine mammals by attacking their digestive system, and scientists are now increasingly asking questions about, for example, the links between diseases in coral and the plastisphere present in the ocean.
The worst aspect of all this is that the smaller the plastic waste particle, the more dangerous it is. While micro and nanoplastics are still imperfectly measured and underestimated, their small size is known to help them pass through organic barriers, thus facilitating the diffusion, anywhere in the world, of the invasive bacteria they may carry.
Consequences on our health?
In view of these findings, one question remains pending: if marine ecosystems and mammals are so severely affected by the plastisphere, what about its impact on human health? We are exposed to it when we consume ocean products and bottled water, and certain bacteria in the plastisphere have already been shown to cause disease in humans, like cholera and gastrointestinal disorders. Yet research into its toxic effects on human health is only in its early stages: more unwelcome discoveries are to be feared in the future if we do not act now to protect the ocean from plastic waste.
