Imagine slicing through a piece of Arctic sea ice and peering at it under a microscope. You’d probably think you wouldn’t find much—just frozen water, some sediment, and maybe a few dormant microbes. But wait! There’s more beneath that icy surface.
Caught in intricate channels of the ice, there’s a vibrant world of dinamic single-celled algae called diatoms. Scientists discovered various Arctic diatom species, particularly from the Navicula genus, thanks to advanced microscopy and DNA techniques.
“You can actually see the diatoms moving, almost like they’re skating on the ice,” remarked Qing Zhang, a postdoc from Stanford, who led the study that recently appeared in the Proceedings of the National Academy of Sciences. “It’s crazy—they remain active down to –15°C, which is totally unexpected.”
This finding marks the coldest temperature recorded at which movement takes place in eukaryotic cells—those fancy cells similar to what makes up humans, trees, and fungi.
What’s even more fascinating: this discovery uncovers a hidden, mobile world residing beneath the frozen waves of the Arctic, prompting serious discussions about how life is adapting as Arctic ice continues to diminish.
Floating Diatoms of the Chukchi Sea
This revelation erupted during a 45-day summer expedition in the Chukchi Sea region, tucked between Alaska and Russia. Scientists aboard the research ship Sikuliaq collected ice cores from twelve different sites.
While some of these ice cores appeared dirty, everything changed under ultra-cool microscopes that were custom-built by the research team. That dirt brought to life the skating diatoms.
The diatoms weren’t just moving a little; they were gliding effortlessly through narrow channels in the ice as if freed from their frozen confines.
According to Zhang, “They secrete a polymer akin to snail mucus, which helps them grip the surface like a rope with an anchor. They then pull on that ‘rope,’ allowing them to glide forward.” This secretion, identified as mucilage, is rich in protein and contains molecular machinery similar to the actin and myosin in our own muscles—magically working even at –15°C!
Surprisingly, compared to their counterparts in warm climates that halt moving below about –1°C, Arctic diatoms are nearly ten times faster on ice at freezing temperatures.
The Dance of Survival in Harsh Conditions
But why would these minicreatures dare to flourish in such a bleak, icy environment?
The answer revolves around light and salt.
Arctic sea ice covers a porous network filled with microscopic brine channels that give dinoflagellates the potential to thrive in specific micro-environments with just the right amount of light and salinity. Staying mobile could be a survival tactic when food and nutrients are crucial.
The research team suggests that diatoms aim for optimal depths in the ice that allow them to soak up the right light, nutrients, and salinity. Staying on the move becomes essential for them to catch narrow windows of opportunity.
While performing gently on ice, only Arctic diatoms have been recorded gliding effortlessly; their counterparts from warmer climates sadly struggled and simply didn’t adhere to icy surfaces.
On both ice and glass, Arctic species exhibited not only rapid movement but remarkable endurance in cold temperatures. Zhang’s team found that these Arctic diatoms robustly held on to icy surfaces, while temperate diatoms fell off easily.
The team suspects that ice-binding proteins might play a crucial role here—similar to substances some cold-adapted bacteria and fish use to stick co-safely in deep chilling regions.
Smart Engineering of Moving Cells
To understand the dynamics behind diatoms’ progressions, the research team added small fluorescent beads to the water and tracked their movements, subsequently mapping out the forces exerted by these diatoms. The beads acted like breadcrumbs, revealing hidden pathways obscured beneath the cells.
The team also created a thermodynamic model illustrating how the internal forces from the myosin motors team up with external drag forces, such as the stickiness of mucilage and fluid around the diatom.
Byching optimized energy conserv barrnags showing how ice diatoms are adapted to shed less internal energy and utilize materials (like their mucilage) that respond differently to cooling traditions compared to temperate species.
The Thriving Ecosystem Beneath the Ice
These Arctic diatoms play a key role in the polar food web. Chains of life-scale up from them to sustain everything from krill to seals and even polar bears. If they are not merely subsisting in ice but also navigating and manipulating their environment, our understanding of nutrient flow and energy dynamics may shift acceptably within one of Earth’s most extreme climates.
As Manu Prakash, a senior author and Stanford bioengineer highlighted, “Underneath the Arctic’s white surface, it’s like living emerald—the everything, evident from the algae. This re-evaluates how vital these organisms are to ecological balance beneath the ice.”
There’s even a thought: the way that these moving diatoms could influence ice growth and melting. Their secretions might actually assist in forming new ice structures.
Timing couldn’t be more relevant; with the Arctic warming at an accelerated pace unlike any other spot on Earth. Several predictions mention that this area could be free of ice in summer as short as 25 to 30 years down the track.
As Prakash noted, “Some colleagues advise that the next 25 to 30 years might witness an ice-free Arctic. Losing those ecosystems would strip our knowledge about extensive branches in our tree of life.”p>
This potential loss looms just when scientists are tackling precisely how those ecosystems function. The specialized microscopes and measures utilized in this research rely heavily on support from organizations such as the National Science Foundation, which is now facing severe budget reductions—reportedly up to a staggering 70% cut for polar research.
If critical infrastructures like the Sikuliaq disappear, or if scientists don’t get ample time to innovate tools like Zhang’s personal sub-zero microscope, innumerable microbial realms could remain explored.
This original story is republished from ZME Science. Want to boost your know-how daily? Subscribe to our newsletter for outstanding science updates.
