5:15 PM - 6:45 PM
[MIS11-P08] The three-dimensional distribution of green snow within the snowpack
under Yukiekubo
Keywords:snow algae, Yukiekubo, Green snow, Mt. Naeba, three-dimensional distribution
During the snowmelt season, a depression with a diameter of several tens of centimeters and a depth of several centimeters, called Yukiekubo, can be found on the snowpack's surface. At the bottom of the Yukiekubo, colored snow, such as red or green, is often observed. The colored snow are formed due to blooms of photosynthesitic microorganisms, called snow algae, which are special species adapted to harsh conditions. However, why snow algae grow intensively in Yukiekubo has not been investigated. In this study, we aimed to reconstruct the three-dimensional distribution of green snow within the snowpack by taking continuous photographs of its vertical sections.
The fieldwork was carried out in April of 2023 on a snowpack in Mt. Naeba in Nagano prefecture in Japan. The green snow samples were corrected and transported to Chiba University and then processed for microscopic observation. The samples were mainly dominated by algae of Chloromonas sp.
The three-dimensional distribution of green snow within the snowpack revealed that the green snow was spread over an area of 15 cm in vertical and 22 cm in horizontal in the center at about 4 cm below the surface of the snow. The horizontal distribution of green snow was biased toward the south from the deepest part of the Yukiekubo. This distribution indicates that algal cells were not simply accumulated by the meltwater flow under the Yukiekubo but were actively aggregated in the snowpack. Motile cells of snow algae are likely to aggregate at the point, where the light and meltwater conditions were most suitable for their reproduction. In the Yokiekubo where the ice layer was observed within the snowpack, green snow was found to be concentrated on the ice layer. This indicates that some algae migrate to the lower layers of the snowpack with the meltwater and accumulate on the top of the impermeable ice layer. These results suggest that algae grow in the abundant meltwater in the snowpack of Yukiekubo and that green snow forms slightly south of the deepest part of the dipression, which is the most preferable part within the snowpack for snow algae in terms of solar radiation and meltwater conditions.
The fieldwork was carried out in April of 2023 on a snowpack in Mt. Naeba in Nagano prefecture in Japan. The green snow samples were corrected and transported to Chiba University and then processed for microscopic observation. The samples were mainly dominated by algae of Chloromonas sp.
The three-dimensional distribution of green snow within the snowpack revealed that the green snow was spread over an area of 15 cm in vertical and 22 cm in horizontal in the center at about 4 cm below the surface of the snow. The horizontal distribution of green snow was biased toward the south from the deepest part of the Yukiekubo. This distribution indicates that algal cells were not simply accumulated by the meltwater flow under the Yukiekubo but were actively aggregated in the snowpack. Motile cells of snow algae are likely to aggregate at the point, where the light and meltwater conditions were most suitable for their reproduction. In the Yokiekubo where the ice layer was observed within the snowpack, green snow was found to be concentrated on the ice layer. This indicates that some algae migrate to the lower layers of the snowpack with the meltwater and accumulate on the top of the impermeable ice layer. These results suggest that algae grow in the abundant meltwater in the snowpack of Yukiekubo and that green snow forms slightly south of the deepest part of the dipression, which is the most preferable part within the snowpack for snow algae in terms of solar radiation and meltwater conditions.