Presentation Information
[ACC45-P05]Chytrid infection of snow algae in Mt. Naeba, Niigata Prefecture, Japan
*Ryotaro Oda1, Ryohei Abe2, Kino Kobayashi2, Nozomu Takeuchi3 (1.Faculty of Science, Chiba University, 2.Graduate School of Science and Engineering, Chiba University, 3.Center for Environmental Remote Sensing Chiba University)
Keywords:
Chytrid,snow algae,parasitism,infection rate,astaxanthin
Parasitic chytrid fungi have been found to parasitize algal cells growing on snowpacks and glaciers worldwide. They have the potential to cause seasonal fluctuations in host populations and to trigger species extinctions, exerting a significant influence on ecosystems. However, their quantitative assessment of snow algae infection within the snowpack remains limited. This study aimed to quantify infection rates of chytrid fungi parasitizing snow algae in snowpack within Japan's alpine zone, determine their vertical and spatial distribution within the snowpack, and examine factors influencing the infection rates.
Samples collected from three sites at different elevations on Mt. Naeba, Niigata Prefecture, between July 2 and July 4, 2025, were analyzed. Microscopic observations revealed that the snowpack contained diverse snow algal cells, classified into 7 morphological types. The algal community structure generally matched that reported in Japanese mountainous areas, with no significant differences among the three sites at different elevations. The overall chytrid infection rate of snow algae in this region was 2.2%. No significant differences in infection rates were observed among the three survey sites or with depth within the snowpack. Conversely, red-pigmented algal cells containing astaxanthin showed a significantly higher infection rate than green algal cells. This suggests that within the snowpack, chytrids parasitize specific algal species or cells possessing certain pigment conditions. Results indicate that the chytrid infection rate of snow algae is nearly constant regardless of elevation or depth, and that infection rates vary by algal type in the snowpack environment of alpine zones in Japan.
Samples collected from three sites at different elevations on Mt. Naeba, Niigata Prefecture, between July 2 and July 4, 2025, were analyzed. Microscopic observations revealed that the snowpack contained diverse snow algal cells, classified into 7 morphological types. The algal community structure generally matched that reported in Japanese mountainous areas, with no significant differences among the three sites at different elevations. The overall chytrid infection rate of snow algae in this region was 2.2%. No significant differences in infection rates were observed among the three survey sites or with depth within the snowpack. Conversely, red-pigmented algal cells containing astaxanthin showed a significantly higher infection rate than green algal cells. This suggests that within the snowpack, chytrids parasitize specific algal species or cells possessing certain pigment conditions. Results indicate that the chytrid infection rate of snow algae is nearly constant regardless of elevation or depth, and that infection rates vary by algal type in the snowpack environment of alpine zones in Japan.