Overview
- Hydrobiologists from the Biology Center of the Czech Academy of Sciences documented the December 2025 event and analyzed lake ice and water samples.
- Microscopy identified the dominant organism as Woronichinia naegeliana, a species that often prevails in Lipno during summer and autumn.
- Weeks of sunshine, calm winds, thin transparent ice, and a brief warm–refreeze period kept biomass at the surface and produced distinctive “cyanobacterial eyes.”
- The visible bloom likely ended after heavy snowfall reduced light penetration beneath the ice late in the year.
- Scientists call the case one of the best-documented under‑ice cyanobacterial events globally and warn that similar winter blooms may become more frequent.