Algae is pushing up the level of microplastics in our meals by hoovering them up from the surrounding water and passing them along the food chain, a study suggests.
Scientists studying algae in the Arctic found that it contained 10 times as many tiny plastic fragments as the water around it, raising concerns that it could be funnelling them into the food chain in huge amounts around the world, posing a threat to wildlife and humans.
Algae provides a key source of nutrition for many species worldwide, meaning microplastics can get passed from one species to another, all the way along the chain to our dinner tables.
The study estimates that every cubic metre of algae contains 31,000 plastic particles – far higher than they expected, and researchers believe the same process could be playing out in rivers and other waterways in the UK and around the world.
In the Arctic Ocean, microplastics can enter the food chain when cod and other fish eat algae and are in turn eaten by other animals, such as seabirdsseals and humans. This passes plastics such as polyethylene, polyester, polypropylene, nylon and acrylic along the food chain. Algae is also a popular food for zooplankton, the tiny micro-organisms that lie at the bottom of the marine food chain in oceans, rivers and other waterways.
Melanie Bergmann, from the Alfred Wegener Institute in Germany, said the study “raises concerns” that algae could be funnelling microplastics into the food chain in disproportionate amounts.
Dr Steve Allen, from the Ocean Frontier Institute at Dalhousie University in Canada, said: “It is very likely this phenomena is occurring in algae around the world. But we need a lot more data to understand how it works and how it’s effect might be felt.
“Tiny plastic fragments have basically been detected in every place scientists have looked in the human body and within a plethora of other species. It is known to change behaviours, growth, fecundity and mortality rates in organisms and many plastic chemicals are known toxins to humans.”
However, the scientists point out that much more research is needed to confirm the study’s findings.
Steve Ormerod, professor of ecology at Cardiff Universitywho was not involved in the study, added: “This Arctic study is important in confirming that algal species in aquatic systems accumulate and increase the concentrations of microplastic particles relative to their surroundings – almost packaging them up in ways that increase the rates at which animals ingest them. It’s very likely that this is a general pattern.”
Deonie Allen, of Birmingham University and Canterbury University in New Zealand, said: “The filamentous algae have a slimy, sticky texture, so it potentially collects microplastic from the sea water, from the surrounding ice and any other source that it passes.
“Once entrapped in the algal slime they travel as if in an elevator to the seafloor – where they can be an important food source for many deep-sea dwellers. Or they are eaten by marine animals on the surface,” she said.
Craig Bennett, chief executive of the Wildlife Trusts, said the implications of the research were globally concerning.
“It really is time for governments and big global companies to wake up to the emerging evidence of just how serious a threat plastic pollution is – not just to our natural environment but to the health of billions of people around the plant,” he said.
“The health threat of microplastics has got all the hallmarks of health scandals that we’ve seen before – from DDT [dangerous banned pesticide] to asbestos – where the warnings are clear but we failed to take action quickly enough. We need to learn from those previous mistakes and be moving far faster on ending the scandal of plastic pollution,” he said.
Dr Bergmann said: “Microplastics have already been detected in human intestines, blood, veins, lungs, placenta and breast milk and can cause inflammatory reactions, but the overall consequences have hardly been researched so far,” she said.
“People in the Arctic are particularly dependent on the marine food web for their protein supply, for example through hunting or fishing. This means that they are also exposed to the microplastics and chemicals contained in it.”
She said there were also concerns about the effect such high concentrations of microplastics could be having on the algae itself.
“Microplastics in or attached to algae could also affect photosynthetic rates by blocking sunlight. In experiments with very high doses of microplastics, small microplastics damaged and entered algal cells, leading to stress responses such as damage of chloroplasts and thus inhibition of photosynthesis,” she said.
“But we don’t yet know how widely this occurs amongst different algae and if this also affects ice algae. It is an impact that could lower the ocean’s buffering capacity, because one service of all plants including algae is that they bind the greenhouse gas CO2 during photosynthesis,” she said.
Algae is found in all types of waters around the world, playing a valuable role in the ecosystem. However, too much of it deprive other wildlife of oxygen and light, as is happening in some UK rivers, where fertiliser washing in from nearby fields can promote algal blooms.
The study is published in the journal Environmental Science and Technology.
#algae #soaking #microplastics #carrying #food