A research team from the Alfred Wegener Institute for Polar and Marine Studies in Germany reports a striking discovery about Melosira arctica, the algae that forms under Arctic sea ice. The study finds that this algae accumulates microplastic particles at a rate far higher than the surrounding seawater, with ten times as many tiny plastic fragments captured inside the dense algal structures. The findings appear in Environmental Science and Technology, a leading journal for environmental science research.
Melosira arctica emerges in large, chainlike filaments under sea ice during the long days of spring and summer. These filaments grow into extensive, meter-scale formations that drift below the ice and eventually sink after the cells die, creating substantial deposits on the seabed. These dead algae deposits play a significant role as a food source for bottom-dwelling organisms and the microbial communities that thrive there, shaping the ecological dynamics of the deep Arctic environment.
The investigation reveals that a substantial amount of microplastic resides on the ocean floor in Arctic waters, with dead algae acting as a sponge for these particles during the melting of sea ice. The researchers measured microplastic concentrations within Melosira arctica and found an average of 19 000 to 31 000 particles per cubic meter, a level roughly tenfold higher than the nondegradable waste found in the surrounding seawater. When the plastic types are broken down, a range of materials appears, including polyethylene, polyester, polypropylene, nylon, and acrylic, indicating a mixed bag of synthetic polymers present in this Arctic ecosystem. These results highlight a direct link between sea ice dynamics, phytoplankton life cycles, and the broader problem of microplastic pollution in polar regions, with implications for marine food webs and carbon cycling.