Sea Ice Ridges Serve as Microbial Biodiversity Hotspots in the Arctic

Nature Communications, 13 March 2026

Rough ridges in Arctic sea ice create habitats that sustain exceptionally diverse microbial communities, which face increasing risk with rising temperatures. These ridges store frozen organic material in the winter, and transform into hotspots of algal productivity in summer, holding up to eight times more algae than nearby smooth ice or surface waters. Environmental changes, including meltwater intrusion and internal freezing during late summer, shift microbial communities in these ridges from predominantly autotrophic to heterotrophic, fundamentally changing how they generate and use energy. This shift transitions ridge ecosystems from being carbon producers to a carbon consumers; in practical terms, it can reduce primary production, alter nutrient cycles, and affect the availability of food for higher organisms. The study suggests that Arctic sea ice decline will significantly change the ecological function and microbial diversity of the Arctic Ocean over coming decades.

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