Scientists have found ice algae loaded with microplastics in the Arctic

These microplastics could seriously endanger the food web.
Mrigakshi Dixit
Polarstern expedition in the Arctic.
Polarstern expedition in the Arctic.

Alfred-Wegener-Institut / Mario Hoppmann 

Microplastics have been detected across a variety of ecosystems as well as in numerous species, from the highest peak on Everest to the human bloodstream. It’s startling to think about where scientists might find these tiny bits of plastic next.  

What’s worse, this type of plastic pollution has the potential to rapidly change the ecosystem, including the pristine environment of the Arctic. 

Now, a new study documents the presence of microplastics in Arctic ice algae and how it may affect the food web of the species that thrive in this icy ecosystem.

Dead algae carry microplastics to the deep sea

The study was led by the Alfred Wegener Institute, and it closely monitored algae called Melosira arctica, which is found beneath the Arctic sea ice. In 2021, the team embarked on the research vessel Polarstern to collect algae and surrounding water samples from ice floes.

The algae species was found to have a ten times higher concentration of microplastic bits than the surrounding seawater.  

During the spring and summer, these algae grow rapidly (forming small cell chains) beneath sea ice. When the algae cells die, they float down to the seafloor. These cells stick together to form lumps beneath the ice, and when the ice melts, they sink to the bottom of the deep sea. 

“The filamentous algae have a slimy, sticky texture, so it potentially collects microplastic from the atmospheric deposition on the sea, the sea water itself, 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, or are eaten by marine animals,” explains Deonie Allen of the University of Canterbury and Birmingham University, who is part of the research team, said in a press release.

Microplastics pass on from one species to another 

Deep-sea animals and bacteria consume algae that have settled on the sediment floor. As a result, microplastic enters the food web. 

Previous research has shown the presence of plastic in zooplankton organisms, and these algae could be one of the potential sources. The chain continues as they are eaten by fish, like polar cod, which are then consumed by seabirds and seals, which are then eaten by polar bears. Humans in the Arctic also rely on seafood, so then the plastic enters our bodies.

This high level of plastic contamination is especially detrimental to the food web. Plastic chemicals can be toxic to humans, and in organisms, they can alter behavior, growth, and fertility and increase the risk of disease. And with the cascading climate change, the Arctic marine creatures and food web may weaken further and suffer significant population declines. 

The findings are reported in the journal Environmental Science and Technology.

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