Snow and Glacial Algae: A Review¹

Area of Science:

• Cryobiology
• Microbial Ecology
• Algal Physiology

Background:

• Snow and glacial algae are widespread primary producers inhabiting extreme cold environments globally.
• They belong to diverse algal groups, primarily Chlamydomonadales and Zygnematales, and contribute to global carbon and water cycles.
• These algae adapt to harsh conditions including low temperatures, high/low irradiance, acidic pH, and desiccation.

Purpose of the Study:

• To provide an overview of snow and glacial algae, their ecological roles, adaptations, and evolutionary history.
• To highlight the importance of advanced molecular techniques in understanding algal diversity and phylogeny.
• To discuss the impact of these algae on cryosphere dynamics and their potential biotechnological applications.

Main Methods:

• Metagenomics, lipidomics, high-throughput sequencing (HTS), multi-gene analysis, and ITS sequencing for species differentiation and phylogenetic analysis.
• Identification of protective secondary metabolites (astaxanthin, purpurogallin) and cryoprotective molecules (ice binding proteins, polyunsaturated fatty acids).
• Molecular phylogenetics to infer evolutionary history and habitat invasion events.

Main Results:

• Snow algae, particularly in the Chlamydomonas-Chloromonas complex, have colonized snow habitats multiple times, with some species showing polyphyletic origins.
• Specialized metabolites and proteins enable survival under extreme cold, high UV, and desiccation.
• Algal blooms significantly reduce snow and ice albedo, accelerating melt and influencing climate feedback loops.

Conclusions:

• Snow and glacial algae are crucial components of polar and alpine ecosystems, influencing biogeochemical cycles and climate.
• Their unique adaptations offer insights into extremophile biology and potential for novel biotechnological products.
• Monitoring snow and glacial algae serves as an indicator for climate change impacts on cryospheric environments.