Arctic algae is contaminated with microplastics, study finds
On the underside of sea ice, there’s a buffet of algae that feeds marine creatures. But new research finds that these sticky strands of algae might not just be a source of nutrition. They could also be a source of plastic pollution entering the marine food web. High concentrations of microplastics have been found in an algae species that clings to the underside of Arctic sea ice, according to a new study published in the scientific journal Environmental Science and Technology. Melanie Bergmann, a biologist at the Helmholtz Centre for Polar and Marine Research at Germany’s Alfred Wegener Institute, has been studying microplastics in marine ecosystems. Though plastics are meant to be durable, items like water bottles, tires, grocery bags and clothing made from synthetic fabrics might break down due to a variety of factors—sunlight, heat, friction. These mass-produced products degrade into smaller and smaller pieces, persisting in the environment for a very long time as microplastics. Any plastic bit less than five millimeters in diameter is considered a microplastic. These particles are easily transported to the most remote stretches of the globe. They’ve been found in the water in the deepest part of the ocean and in the snowpack near the top of Mount Everest. Researchers have been especially concerned about microplastic prevalence in the Arctic, a region already facing other forms of environmental upheaval. Plastics have been found in Arctic waters, seafloor sediments and sea ice, but there hasn’t been much research yet on microplastics on algae at the base of the food chain in Arctic environments. For the new study, the researchers looked at the algae Melosira arctica, which is distributed widely across Arctic waters, including the Chukchi Sea. Though the species is singlecelled, it clumps together in strands, mats and curtain-like formations up to 10 feet long under annual and multi-year sea ice. This algae grows quickly in the spring and summer, and it feeds a variety of zooplankton species near the sea surface. When sea ice melts, these algae clumps sink to the seafloor, feeding other critters like brittle stars and sea cucumbers. During an expedition with the research vessel Polarstern in summer 2021, Bergmann and her team collected Melosira arctica samples as well as seawater samples from three locations in the Fram Strait between Greenland and Svalbard. The researchers were surprised to find that the algae samples collected in the study contained an average of ten times as many microplastic particles as the surrounding seawater. “I am quite certain that we will find [microplastics] in many algal samples if we look,” Bergmann told the Nugget. “This is because we find microplastics everywhere we look. In addition, many algae have a slimy or sticky surface that floating microplastics can adhere to.” Most of the microplastics found in the study were under 10 microns, smaller than the diameter of a wool fiber. They came from nearly every type of plastic source—including polyethylene, polyester, nylon and acrylic. Douglas Causey, a biology professor at the University of Alaska Anchorage who was not involved in the study, said this research is significant because it is one of the first to document the presence of microplastics in a marine algae species commonly associated with ice. “This is not good news,” Causey told the Nugget. “Not only is this algae common in the Arctic, it also forms the food base for most of the Arctic marine food webs.” Causey has been studying seabirds in the Aleutian Islands for decades. He and his colleagues have found that birds important for subsistence, like auklets and murres, are contaminated with plastic pollution. “Our own research on plastics in seabirds indicates that the plastic pollution only concentrates as we move from plankton and invertebrates that eat marine algae to the fish that eat the plankton to the marine mammals and birds that eat the fish, and humans that catch the fish,” Causey said. He added that the new report is not all bad news. “We now have very clear evidence of where the microplastics are found, what they are composed of, and which species are most at risk. This information can be used to help design some ways to protect the marine environment.” Bergmann said there’s still not much data on plastic burdens in other marine species. In a future expedition, she plans to sample animals from the Arctic seafloor to study the extent bottom-dwelling critters are affected by microplastics pollution. She said she’s also planning to work with citizen scientists to collect feces of Arctic wildlife such as polar bears and reindeer for similar analyses. She said more work from medical researchers would be needed to understand how microplastics from these marine sources affect human health. “I think we need to find out how plastic has invaded the food web, especially those organisms that are linked with spheres that experience particularly high pollution levels, such as sea ice and the deep seafloor, or animals that are eaten by humans,” Bergmann said. “Of course, if we know that it also causes harm to humans, the pressure to address the problem would increase.” Bergmann will accompany the German delegation to the second round of the UN’s global plastics treaty negotiations which are taking place in Paris next week. “Based on the scientific evidence that we have, I will recommend imposing caps on the production of new plastics, which could save a lot of plastic waste and pollution,” Bergmann said. “In addition, we need regulation to simplify and standardize the composition of plastics including chemicals to actually enable recycling of essential plastics and to reduce the risk posed by chemicals to human and environmental health.” In November of this year, Iceland will also host the Second International Symposium on Plastics in the Arctic and Sub-Arctic Region.