5:15 PM - 6:30 PM
[ACG39-P15] A study on parasitic chytrids of glacier algae on Gulkana Glacier in Alaska
Keywords:chytrids, glacier algae, fungi, cryoconite hole, glacier
Glacier algae are photosynthetic microbes growing on the ablating surface of Arctic glaciers. Because the algae have dark-colored pigments in their cells, they reduce surface albedo and accelerate the melting of the glacier surface. Kol(1942) reported that one of the glacier algae, Ancylonema (A.) nordenskioldii, on glaciers in Alaska was often observed to be parasitized by Chytrids. Chytrids is one of the groups of fungus, which form zoospores with a flagellum in their life cycle. Most of Chytrid is parasitic in various organisms including vascular plants, algae, invertebrates, and vertebrates. Parasitic chytrids have an great impact on ecosystems, causing extinction and/or population dynamics of host species. Therefore, it is important for assessment of ecosystems and melting process of glaciers to understand ecology of chytrids parasitizing glacier algae. The purpose of this study is to describe morphology and distribution of chytrids and to quantify the frequency of parasitism on algal cells using snow and ice samples collected on the bare ice surface in Gulkana Glacier in Alaska.
The snow and ice samples used for the analysis was collected on cryoconite hole and ice surface of three sites (1385 m, 1470 m, 1585 m) of different altitudes on Gulkana Glacier in Alaska in August, 2015. The fluorescent dye, Calcoflor White, which specifically stains fungi (chitin), was used for microscopy. Morphological characteristics of chytrids parasitizing glacier algal cells was observed with a fluorescence microscope and the frequency of parasitism on algae was calculated by counting the presence or absence of Chytrid on the algal cell. Furthermore, size of Chytrids and algae were measured using microscopic photographs and an image processing application (Image J).
A number of glacier algae, A. nordenskioldii, were observed to be parasitized by Chytrids in the samples. There were mainly three types of the rhizoid of chytrids observed within the algal cells: Type A, shorter rhizoid; Type B, longer rhizoid with a bulge; and Type C, rhizoid extending out of the algal cells. Different life stage of these chytrids can be recognized based on their size and morphology, indicating that the chytrids actively propagate on this glacier. The frequency of parasitism on the algae, was significantly higher for algae in cryoconite holes (20 %) than those on ice surface (4%). This indicates that chytrids are more active in cryoconite holes compared with on the ice surface. Size of both chytrids and algal cells were larger on ice surface than in cryoconite holes. This indicates that Chytrids preferentially parasitize larger algal cells. Results suggest that Chytrids are abundant in cryoconite holes, thus, process of forming and decay of cryoconite holes may influence their activity and parasitism to algae on the entire glacier.
The snow and ice samples used for the analysis was collected on cryoconite hole and ice surface of three sites (1385 m, 1470 m, 1585 m) of different altitudes on Gulkana Glacier in Alaska in August, 2015. The fluorescent dye, Calcoflor White, which specifically stains fungi (chitin), was used for microscopy. Morphological characteristics of chytrids parasitizing glacier algal cells was observed with a fluorescence microscope and the frequency of parasitism on algae was calculated by counting the presence or absence of Chytrid on the algal cell. Furthermore, size of Chytrids and algae were measured using microscopic photographs and an image processing application (Image J).
A number of glacier algae, A. nordenskioldii, were observed to be parasitized by Chytrids in the samples. There were mainly three types of the rhizoid of chytrids observed within the algal cells: Type A, shorter rhizoid; Type B, longer rhizoid with a bulge; and Type C, rhizoid extending out of the algal cells. Different life stage of these chytrids can be recognized based on their size and morphology, indicating that the chytrids actively propagate on this glacier. The frequency of parasitism on the algae, was significantly higher for algae in cryoconite holes (20 %) than those on ice surface (4%). This indicates that chytrids are more active in cryoconite holes compared with on the ice surface. Size of both chytrids and algal cells were larger on ice surface than in cryoconite holes. This indicates that Chytrids preferentially parasitize larger algal cells. Results suggest that Chytrids are abundant in cryoconite holes, thus, process of forming and decay of cryoconite holes may influence their activity and parasitism to algae on the entire glacier.