[M-IS12] Mountain Science

[MIS12-10] Impacts on snow ecosystems: Snow algae blooms in seasonal snowpacks and perennial snow valleys in mountainous regions of the Japanese Archipelago

★Invited Papers

*Takumi Suzuki¹, Jun Uetake², Nozomu Takeuchi³ (1.Japan Aerospace Exploration Agency (JAXA), Earth Observation Research Center (EORC), 2.Field Science Center for Northern Biosphere, Hokkaido University, 3.Graduate School of Science, Chiba University)

Keywords:Snow algae, Seasonal snow packs, Perennial snow valleys , Ecosystem

Snow algae thrive on melting snow surfaces in various mountainous regions, including the Japanese Archipelago. Notably, the phenomenon of snow algae blooms is observable on alpine snow cover during the melting season. The diverse snow cover in Japanese mountains consists of seasonal snowpacks and perennial snow valleys, with the former further categorized into alpine and forest types based on surrounding vegetation. This study aims to clarify the relationship between environmental conditions and snow algae blooms, and to discuss the effects on snow ecosystems caused by changes in snow environments associated with future climate change. Examinations conducted on Mt. Gassan's seasonal snowpacks revealed the occurrence of red snow in alpine areas and green snow in forested regions, suggesting a correlation with the surrounding vegetation. The opening of deciduous broad-leaved trees was identified as a factor leading to increased nutrient levels, thereby promoting the growth of algal cells. Analysis of perennial snow in Tsurugi-sawa snow valleys at Mt. Tateyama highlighted the influence of topographical factors and seasonal variations in solar altitude on the occurrence of red snow and orange snow in summer, and yellow-green snow in autumn. Phylogenetic analysis of eukaryotic microbial communities in samples from Mt. Gassan and Tsurugi-sawa snow valleys revealed distinct dominant algal species in alpine, forest, and snow valley environments. This disparity indicates that dispersal processes, as well as variations in light, nutrients, and snow conditions, contribute to the prevalence of different algal species in these environments. The current rise in temperature due to global warming is expected to have a significant impact on the snow environment in the Japanese archipelago, but the changes will vary according to region and altitude. In the future, the timing and extent of the appearance of green snow in mid- and low-mountain forested areas and red snow in alpine areas is expected to shrink, while the extent of red snow in high-altitude alpine areas is expected to expand and the timing of the appearance of colored snow in perennial snow valleys is expected to be limited. In the long term, global warming is expected to cause changes in the vegetation in mountain areas, and the algal communities in the snow cover of forested and alpine areas will also change. Although there are still many unresolved aspects of the snow ecosystem in the mountainous regions of the Japanese archipelago, further understanding of snow algae blooms is needed to predict the response of snow ecosystem to the future climate change.