Across the Arctic ice, diatoms persevere in a world of brine channels and shimmering ice. Our study provides direct cellular observations of ice-dwelling diatoms within frozen matrices, revealing an unexpected capability: ice gliding. Unlike temperate diatoms, these Arctic relatives appear to navigate by gliding along icy substrates, a skill that opens access to light, nutrients, and microhabitats embedded in the ice. The behavior emerges from a combination of specialized substrate interactions and extraordinary cold tolerance, enabling diatoms to traverse the ice matrix rather than remaining passively stranded. In this report, we translate these observations into physical terms using thermo-hydrodynamic modeling to explain how cold motility can be achieved through energy-efficient strategies and optimized mucilage properties. The findings illuminate phytoplankton adaptability in extreme environments and bear on ecological resilience amid climate change.
Direct Observations: Ice-Gliding in Arctic Diatoms
We conducted near-molecule scale observations of diatoms embedded in ice, documenting periods of sustained, directional movement along crystal lattices and within thin brine-infused channels. This ice gliding is distinct from active swimming and relies on subtle interactions between the diatom cell surface and the ice substrate. The diatoms maintain locomotion at temperatures near the ice’s eutectic point, revealing a previously unappreciated lower bound for motility in eukaryotic cells. Observations in the Arctic environment show these diatoms can exploit microhabitats inside the ice, where light penetrates through translucent layers and nutrients diffuse along brine channels.
Mechanisms Behind Ice Gliding
Substrate Interactions and Mucilage
Key to ice gliding are the diatom’s secretions—thin mucilage films that interact with the ice surface to reduce drag and stabilize contact with the substrate. These mucilage layers adapt in viscosity and conductivity to colder temperatures, enabling a low-resistance glide even when external water is frozen. The mucilage acts as a lubricating cushion, while surface molecules on the diatom cell envelope promote alignment with microstructures in the ice, guiding directional movement across the lattice.
Thermo-Hydrodynamic Modeling
Complementing the cellular observations, thermo-hydrodynamic modeling demonstrates how energy efficiency and substrate-assisted flow contribute to sustained motility. Models indicate that diatoms can balance metabolic energy with mechanical work by modulating mucilage production, reducing thrust requirements, and leveraging local temperature gradients across the ice–water interface. In essence, Arctic diatoms optimize their energy budget to maintain movement in an environment where every degree and every molecule of mucus matters for propulsion.
Ecological and Astrobiological Implications
The ability to glide on ice expands the potential ecological niches for Arctic diatoms. By navigating within the ice, these organisms can access light pockets and nutrient-rich microhabitats that are not available to non-motile relatives, contributing to primary production during seasons when surface waters are frozen. This behavioral plasticity enhances ecological resilience to climate change, as diatoms may shift their habitats in response to thinning ice and shifting light regimes. Moreover, the findings have resonance for astrobiology: icy worlds beyond Earth may harbor life that uses similar low-temperature motility strategies. Understanding how eukaryotic cells reduce energy costs while negotiating solid substrates informs the search for life in subzero environments.
Concluding Thoughts and Future Directions
By establishing a record-low temperature limit for motility in a eukaryotic cell, ice-gliding diatoms open new questions about the evolution of locomotion under extreme cold. Future work will quantify the energetic costs of gliding, characterize the exact mucilage composition across diatom species, and refine thermo-hydrodynamic models with in situ measurements from polar ice. These efforts will improve our ability to predict how polar ecosystems respond to warming climates and altered ice physics, and will contribute to broader theories of life in icy habitats, including the broader field of astrobiology. The study underscores that even in the harshest extremes, microbial behavior adapts to unlock ecological opportunities, reshaping our understanding of resilience at the edge of life.
