The smaller a particle is, the more organisms it can enter. Plastics can break down so small that they enter the individual cells of algae or zooplankton that feed on them.
Researchers still can’t say if all that microplastic is doing harm arctic honeydew. But additional laboratory research has found that plastic particles can be toxic to other forms of algae. “In experiments with very high doses of microplastics, small microplastics damaged and entered algae cells, triggering stress responses such as chloroplast damage and thus inhibition of photosynthesis,” Bergmann says. .
There’s another concern, too: If enough plastic builds up in the algae, it could block sunlight from reaching the cells, further interfering with photosynthesis and growth. “This study really contributes to a growing body of research showing that these microscopic organisms and these microscopic plastics can escalate into a really macroscopic problem,” says Anja Brandon, associate director for US plastics policy at the Ocean Conservancy. , who wasn’t involved in the study. “These algae in the Arctic and the phytoplankton throughout the marine environment make up the fundamental backbone of the marine food web.”
But the proliferation of plastic could devastate that network. As summer temperatures rise and Arctic sea ice deteriorates, more and more clumps of algae may break free and sink, taking those microplastics with them into new ecosystems. That could be why scientists are also finding droplets of the particles in the sediments of the Arctic Ocean. “There’s a whole community right below where the ice is melting,” says Steve Allen, a microplastics researcher at the Ocean Frontiers Institute and co-author of the new paper. Sinking algae are a kind of “conveyor belt” of food for benthic creatures like sea cucumbers and brittle stars, he says.
In this sensitive ecosystem, food is relatively scarce compared to, for example, a tropical reef. If a sea cucumber already gets by with limited amounts of food dripping from the surface, it would be bad to load that food up with inedible plastic. This is known as “food dilution” and has been shown be a problem for other small animals, which fill up on microplastics while reducing their appetite for real food.
Jagged plastic particles can also cause severe scarring in the gut, as recently demonstrated in seabirds with new disease known as plasticosis. And that’s not to mention the potential chemical contamination of an animal’s digestive system: at least 10,000 chemicals have been used to make plastic polymers, a quarter of which scientists considers worrisome.
Photo: Julian Gutt/Alfred Wegener Institute