In a remarkable breakthrough, researchers at Stanford University have discovered that Arctic diatoms—microscopic, single-celled algae with glass-like walls—can actively glide through channels in frozen sea ice at temperatures as low as −15 °C. This sets a new record for the coldest movement ever observed in complex living cells, overturning long-held assumptions about life in extreme cold.
A Hidden World in the Ice
When scientists extract ice cores from the edges of the Arctic polar cap, they often notice faint brown streaks. These streaks are diatoms—tiny algae encased in silica walls. While their presence in sea ice has long been known, they were generally assumed to be trapped and inactive, and thus rarely studied in detail.
How and Where the Research Was Conducted
The scientists carried out their research during an Arctic expedition in the Chukchi Sea aboard the research U.S. vessel Sikuliaq, focusing on sea ice from regions near the polar cap’s outer edges. They used specially designed microscopes capable of operating at sub-zero temperatures to observe the diatoms directly in their natural icy environment. By carefully extracting small sections of ice and keeping them frozen during observation, the team was able to witness the algae’s unique movements without disturbing their natural state. This approach allowed them to study the cells’ behavior in conditions very close to those they experience in the wild.
The research vessel Sikuliaq is owned by the National Science Foundation and operated by the University of Alaska Fairbanks. The researcher came from the Prakash Lab and the lab of Kevin Arrigo, professor of Earth system science in the Stanford Doerr School of Sustainability.
The Discovery
Using a custom-built sub-zero temperature microscope during an Arctic expedition, scientists observed these diatoms exhibiting motility at unprecedented low temperatures. The algae's movement was facilitated by actin filaments within their cells, enabling them to glide across the icy surfaces. This unique adaptation allows the algae to navigate the frozen environment and remain biologically active even in extreme cold. This finding is particularly significant as it was previously believed that such organisms would be dormant in frozen conditions.
Implications for Arctic Ecosystems
The ability of diatoms to thrive and move in sub-zero conditions suggests they may play a far more dynamic role in Arctic ecosystems than previously understood. Their activity influences nutrient cycling and food web dynamics, providing an essential energy source at the very base of the food chain. Beyond the Arctic, this discovery also offers insight into the resilience of life in extreme environments on Earth and even on icy worlds beyond our planet.
Arctic Food Chain: Why Algae Matter
Sea ice algae form the foundation of the Arctic marine food web. Tiny zooplankton such as copepods, krill, and amphipods graze directly on the algae. These fat-rich organisms sustain Arctic cod and other small fish, which are then eaten by seals, walruses, and whales. At the top of the food chain, polar bears depend on seals, whose survival ultimately relies on the productivity of sea ice algae.
In this way, the survival of the Arctic’s largest predators can be traced back to the resilience of its smallest organisms—microscopic algae thriving in ice at −15 °C.
Sources: StanfordReport, Bioengineer.org, PNAS
Image: ESA / Karley Campbell / UiT
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