ヒマラヤの氷河生態系

• Main Author: 幸島, 司郎
• Other Authors: Kohshima, Shiro, コウシマ, シロウ
• Format: Report
• Language: Japanese
• Published: 京都大学ヒマラヤ研究会 2007
• Subjects: 225.8; ice core; Copepods
• Online Access: http://hdl.handle.net/2433/185959; https://doi.org/10.14989/HSM.8.113

ヒマラヤの標高5千メートルを超える高山域には, 氷河という雪と氷の世界が広がっている. 氷河や雪渓, 積雪など, 水が主に雪や氷といった固体として存在する雪氷圏は, その寒冷な環境条件のため, 長い間無生物的世界であると見なされ, つい最近まで本格的な生物学研究の対象とはされてこなかった. 特に, 変温動物である無脊椎動物の生息環境としては, ほとんど無視されてきた. しかし筆者らの調査によって, 実は氷河にも見虫や甲殻類をはじめとする様々な生物が生息しており, 特異な生態系が成立していることが明らかになってきた. 本稿ではヒマラヤ域の氷河に生息する生物の生態を紹介するとともに, この地域の氷河生態系の特性を概説する. Biological activity on glaciers has been believed to be extremely limited. However, in Himalayan glaciers, we found biotic communities including various cold-tolerant insects and copepods that were feeding on algae and bacteria growing in the snow and ice. Thus, the glaciers are simple and relatively closed ecosystems sustained by primary production in the snow and ice. Since microorganisms growing on the glacier are stored in the glacial strata every year, ice-core samples contain many layers with these microorganisms. Recently, it was shown that these microorganisms in the ice-core could be new environmental markers for past environment. It was also suggested that the microbial activity on the glacier could affect the mass balance and fluctuation of the Himalayan glaciers because blooms of algae and bacteria on the glacier was found to reduce the surface albedo and significantly affect the glacier melting.