China Dialogue Ocean spoke to Dick Vethaak, a retired professor of ecotoxicology (the study of how toxins affect organisms and ecosystems) and water quality: \u201cWe have introduced a completely new niche of substrates, used as a homeland for distinct microorganism communities. I refer to this as a plastic time bomb \u2013 the ground for the next pandemic.\u201d<\/p>\n\n\n\n
He is not the only person with such concerns.<\/p>\n\n\n\n
Every corner of the ocean<\/h2>\n\n\n\n
Plastics are everywhere<\/a> humans have looked in the marine environment, from microscopic fragments encased in Arctic ice, to bags drifting on the deepest ocean floors.<\/p>\n\n\n\n Most of this enters the ocean from land<\/a>, with rivers believed to be the primary source of contamination. Once it enters the water, wind and waves break and shape it as sunlight degrades it, often transforming waste items into smaller and smaller fragments.<\/p>\n\n\n\n Legally binding rules designed to end this pollution are being drawn up under the auspices of the United Nations. To date, progress has been difficult<\/a>, and the outcome is still uncertain.<\/p>\n\n\n\n Adding to the problem, there are suggestions that the fossil fuel industry could pivot from energy to plastic production.<\/p>\n\n\n\n \u201cThe industry sees plastics as their plan B: if they can\u2019t use fossil fuels as an energy source, then they will use it for plastic products,\u201d says Bethanie Carney Almroth, a professor of ecotoxicology and environmental science at the University of Gothenburg, Sweden.<\/p>\n\n\n\n Carney Almroth, who is involved in the UN plastic treaty negotiations<\/a>, is concerned by this concerted push for increasing plastics production: \u201cWe have too much plastic: the planet and human societies cannot tolerate more.\u201d<\/p>\n\n\n\n Almroth tells China Dialogue Ocean that microorganisms thriving on plastics are the latest addition to the list of dangers posed by marine plastic.<\/p>\n\n\n\n The seas are home to a huge variety of microorganisms. Scientists working on a study of Pacific Ocean coral reefs which concluded last year, were so surprised by the number they found that they suggested<\/a> revising estimates of Earth\u2019s microbial diversity upwards.<\/p>\n\n\n\n Wood, metal and any other material adrift at sea is rapidly colonised. As plastic has become ubiquitous in the ocean, our discarded waste has become a new type of home for life.<\/p>\n\n\n\n In 2013, the marine microbiologist Linda Amaral-Zettler and her colleagues coined the term \u201cplastisphere<\/a>\u201d to describe the layers of organisms they found on plastic samples from the North Atlantic Subtropical Gyre (a part of one of Earth\u2019s five major circulating ocean currents, which coalesce floating plastic into rubbish patches). Their study said the communities of microbes living on plastic debris were different from those in nearby water, \u201cimplying that plastic serves as a novel ecological habitat in the open ocean\u201d.<\/p>\n\n\n\n Plastics endure, meaning microbial communities that build up on them can travel long distances, potentially bringing species far beyond their normal geographical range. They may also degrade into tiny pieces, which accumulate in animals, including those intended for human consumption<\/a>.<\/p>\n\n\n\n Plastispheres are now a major global environmental concern.<\/p>\n\n\n\n One team of researchers has been studying how layers of microorganisms called biofilms develop on plastics in the Mediterranean and North Atlantic oceans, through a project called MicroplastiX<\/a>. One of the project\u2019s marine ecologists, <\/strong>Raffaella Casotti, told China Dialogue Ocean that \u201cin the Gulf of Naples, a densely urbanised area, a wide variety of algae, invertebrates, and fungi grows on all microplastics sampled.\u201d<\/p>\n\n\n\n Though most of the microorganisms that have been detected in the Mediterranean plastisphere are harmless, the researchers also found<\/a> <\/strong>Vibrio<\/em> bacteria in higher concentrations on plastic than in the surrounding waters. Some types of bacteria of the Vibrio<\/em> genus are known to cause disease in shellfish \u2013 and the humans who eat them.<\/p>\n\n\n\n Casotti\u2019s team fed<\/a> sea \u200b\u200burchins with either pristine or biofilm-laden plastic. Those fed the colonised plastic displayed a significantly stronger immune response. \u201cThe presence of a plastisphere doesn\u2019t kill them, but leads to the immune system\u2019s reaction,\u201d explains Casotti. \u201cOur hypothesis is that the microorganism on plastic might affect the sea urchin\u2019s reproduction.\u201d<\/p>\n\n\n\n In both laboratory-based and wild studies, scientists have found that colonised microplastics affect multitudes of species. The problems they cause range from impaired feeding, reproduction and fitness in corals and bivalves, to disease in aquaculture facilities.<\/p>\n\n\n\n Microplastics are not just found in the small filter feeders, such as oysters, that consume them directly in shallow waters.<\/p>\n\n\n\n \u201cWe found microplastics present in surface, mid-water and deep-sea species like clams<\/a>, yellowfin tuna<\/a> and vampire squid<\/a>,\u201d says Anne Justino, a researcher at the Federal Rural University of Pernambucoian in Brazil. Her work reveals that microplastic transfer into oceanic predators occurs when they eat contaminated prey, rather than through directly ingesting debris.<\/p>\n\n\n\n Justino\u2019s team, which is also involved in the MicroplastiX project, is now working with fishery industries to assess the level of microplastic contamination in fish muscles \u2013 the main part eaten by humans.<\/p>\n\n\n\n Currently, researchers do not have a clear picture of how humans are exposed to plastics and what the consequences of any exposure might be.<\/p>\n\n\n\n One process that has been shown to remove some accumulated microplastics in seafood and thus reduce the potential for human health impacts is called depuration. This is where animals are placed in clean, flowing water to try and purge contaminants from their digestive systems.<\/p>\n\n\n\n But there are suggestions that oceanic plastispheres might still generate health problems for humans.<\/p>\n\n\n\n Karen Shapiro, a waterborne zoonoses specialist at the UC Davis Veterinary Medicine academic centre in California, USA, has shown<\/a> how microscopic parasites like Toxoplasma gondii<\/em> can quickly form colonies on floating plastic debris. This parasite is known to live inside shellfish, which then infect humans who eat them raw. Preliminary studies from Shapiro\u2019s group and others show that Toxoplasma gondii<\/em> can survive on plastic debris for several months.<\/p>\n\n\n\n Shapiro postulates that the plastisphere is bringing pathogens to areas where they would not otherwise be. She is cautious about drawing conclusions, however: \u201cWe know that plastispheres make their ways in our bodies, but we still don\u2019t understand what they do to us. We lack clear papers directly correlating consumption of colonised microplastics and health effects for people.\u201d<\/p>\n\n\n\n Studies have found that plastispheres constitute happy islands for superbugs.<\/p>\n\n\n\n The use of antibiotics on fish farms can promote the flourishing<\/a> of resistant bacteria in marine environments; such antibiotic-immune organisms might then flow into oceans via wastewater-treatment plants.<\/p>\n\n\n\n In 2021, researchers at the New Jersey Institute of Technology in Newark reported<\/a> that microplastics from shellfish host bacteria resistant to antibiotics, and that these superbugs could survive longer on microplastics than when free-floating. South Korean researchers also found<\/a> abundant antimicrobial genes when analysing microbial communities living on plastic in the North Pacific Gyre.<\/p>\n\n\n\n But finding a direct correlation between the plastisphere and antibiotic-resistant infections in humans is incredibly difficult.<\/p>\n\n\n\n \u201cThe only way to definitively prove that the plastisphere contributes to disease outbreak,\u201d says Vethaak, \u201cis to assess the risk for human health from plastic-associated pathogens in populations suffering from occurring epidemics and living closer to highly polluted areas.\u201d<\/p>\n\n\n\n He strongly believes that \u201cplastic debris might serve as a vector for the spreading of diseases and antibiotic-resistant microorganisms in disaster areas [such as war zones and regions hit by extreme weather] with documented high levels of plastic\u201d.<\/p>\n\n\n\n Plastic pollution has been seen in every part of the ocean and detected in every marine creature where it has been sought.<\/p>\n\n\n\nEnter the plastisphere<\/h2>\n\n\n\n
Hitchhikers\u2019 health impacts<\/h2>\n\n\n\n
![\"wide](\"https:\/\/dialogue.earth\/content\/uploads\/2024\/02\/Mediterranean-Sea-plastic_Alamy_ACEHER-scaled.jpg\")
<\/div>Up the chain<\/h2>\n\n\n\n
Superbugs thriving on plastic<\/h2>\n\n\n\n
![\"plastic](\"https:\/\/dialogue.earth\/content\/uploads\/2024\/02\/ocean-pollution_Alamy_2CC9GBM-scaled.jpg\")
<\/div>The high cost of cheap plastic<\/h2>\n\n\n\n