[A-CG52] Science in the Arctic Region

[ACG52-07] The prevalence of infection of chytrid fungus on glacier algae on Qaanaaq Glacier, northwestern Greenland

*Kino Kobayashi¹, Rigen Shimada², Motoshi Nishimura³, Kenshiro Arie², Takumi Suzuki², MASATO ONO⁴, Nozomu Takeuchi¹ (1.Chiba University, 2.Japan Aerospace Exploration Agency, 3. Shinshu University, 4.Kyoto University)

Keywords:chytrids, fungi, glacier algae, glacier, Qaanaaq, Greenland

The melting of Arctic glaciers has been accelerating due to the darkening of glacier surfaces. One of the reasons for the darkening is the blooming of glacier algae, photosynthetic microorganisms with dark-colored pigments in their cells. These algae can be parasitized by chytrid fungus. Chytrids are one of the groups of fungi and are characterized by having zoospores in their life cycle. Parasitic chytrids have a great impact on ecosystems, causing population dynamics and/or extinction of host species. Therefore, chytrids parasitizing glacier algae may suppress algal blooms and the darkening of glaciers. In the Greenland Ice Sheet, the darkening of glaciers due to algal blooms has been reported, and various studies have been conducted on microorganisms such as glacier algae, particularly in the Qaanaaq Glacier in northwest Greenland; however, no research has been conducted on the chytrids parasitizing glacier algae. This study focuses on the chytrids parasitizing glacier algae on the Qaanaaq Glacier in northwest Greenland and aims to clarify the morphology of the chytrids and the prevalence of infection of chytrids on glacier algae.
The samples used for the analysis were collected on ice surfaces on the Qaanaaq Glacier, northwestern Greenland, from July 24 to August 17, 2024. The samples were added with a fluorescent dye, Calcofluor White, which specifically stains fungi (chitin). The morphological characteristics of chytrids parasitizing glacier algal cells were observed under a fluorescence microscope. The prevalence of infection of chytrids was calculated by counting the presence or absence of chytrids on the algal cells.
Chytrids parasitizing glacier algae genus Ancylonema were observed in the ice samples. Three types of chytrids were observed to parasitize glacier algae, classified based on the morphology of the rhizoids that extend from the chytrid into the algal cell. The prevalence of infection of the Ancylonema algae was approximately 5% and differed between two different species of the Ancylonema algae. The chytrid morphology and prevalence of infection on ice surfaces were similar to those reported on a glacier in Alaska. These results suggest that chytrids are abundant on the surface of the Qaanaaq Glacier in northwest Greenland and that chytrid infection on algae may affect the algal blooms.