Scientists revive 7,000-year-old algae, offering glimpse into ancient marine life

Scientists have successfully revived microalgae that lay dormant for nearly 7,000 years beneath the Baltic Sea, offering a rare opportunity to study ancient marine ecosystems and their evolutionary responses to environmental change. The research, published in The ISME Journal, presents a detailed account of how long-buried organisms can act as biological time capsules, revealing genetic adaptations across millennia.

The international research team focused on Skeletonema marinoi, a common species of diatom found in coastal marine environments. By extracting samples from various layers of seabed sediment and restoring them to favorable conditions, researchers were able to reactivate the algae’s photosynthetic functions and observe their growth. The oldest viable strain dated back over 6,800 years.

Genetic comparisons between the revived ancient strains and their modern counterparts showed measurable differences, suggesting gradual adaptation over thousands of years. Despite their prolonged dormancy, the ancient algae demonstrated normal oxygen production and stable growth rates, reinforcing the concept of dormancy as a survival mechanism rather than mere stasis.

The study contributes to the emerging field of resurrection ecology, which examines long-inactive organisms to assess how historical environmental pressures shaped their evolution. According to the researchers, the findings may help improve predictions of how phytoplankton—and by extension, broader marine ecosystems—could respond to future climate scenarios.

Dormancy in S. marinoi involves the formation of specialized resting cells with thickened walls and internal energy stores. These cells sink to the seabed during unfavorable periods and can endure in oxygen-deprived, dark conditions for extended periods. Once re-exposed to light and nutrients, the cells resume metabolic activity, including photosynthesis and reproduction.