Segawa Takahiro, Takeuchi Nozomu, Matsuzaki Ryo, Yonezawa Takahiro, Yoshikawa Kenji
Center for Life Science Research, University of Yamanashi, 1110, Shimokato, Chuo, Yamanashi, 409-3898, Japan.
Department of Earth Sciences, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
ISME J. 2025 Jan 2;19(1). doi: 10.1093/ismejo/wraf197.
Red-pigmented snow algae are cold-adapted (including cryophilic) photosynthetic microbes commonly found in polar and alpine snowpacks worldwide, but their dispersal across isolated cryospheres remains poorly understood. We report the occurrence of snow algae on Maunakea, Hawai'i, the most isolated cryosphere in the world, during an unusually prolonged summer snow retention event in 2023 associated with La Niña conditions. Red-pigmented algal cells were observed in snow samples collected during this event. ITS2 amplicon sequencing identified two major Chlorophyta groups: the cosmopolitan Sanguina group and the endemic Chloromonadinia snow group. The cosmopolitan Sanguina group disperses into Hawai'i from other cryospheres under present climate conditions, whereas the endemic Chloromonadinia assemblage shows multiple arrivals, with the largest Hawaiian clade indicating colonization between ~253 and 130 ka, overlapping the Pohakuloa glaciation (MIS 6) when Maunakea's summit was ice-capped. This study shows how specific climate conditions, such as glaciation, provided long-term habitats that enabled the establishment of distinct snow algae lineages, highlighting the timing, and processes of their dispersal as shaped by glaciation and climate change.
红色色素的雪藻是适应寒冷（包括嗜冷）的光合微生物，常见于全球极地和高山积雪中，但它们在孤立冰冻圈中的传播情况仍知之甚少。我们报告了在夏威夷莫纳克亚山出现雪藻的情况，莫纳克亚山是世界上最孤立的冰冻圈，这一情况发生在2023年与拉尼娜现象相关的异常持久的夏季积雪留存事件期间。在此事件中采集的雪样本中观察到了红色色素的藻类细胞。ITS2扩增子测序确定了两个主要的绿藻门类群：世界性的血藻属类群和特有的雪绿藻单胞藻类群。在当前气候条件下，世界性的血藻属类群从其他冰冻圈扩散到夏威夷，而特有的雪绿藻单胞藻类群显示有多次迁入，夏威夷最大的分支表明其定殖时间在约25.3万年至13万年之间，与莫纳克亚山山顶被冰雪覆盖的波哈库洛阿冰川作用（海洋同位素阶段6）重叠。这项研究展示了特定的气候条件，如冰川作用，如何提供长期栖息地，使得不同的雪藻谱系得以建立，突出了冰川作用和气候变化对其传播时间和过程的影响。
