2:15 PM - 2:30 PM
[ACG42-13] The altitudinal distribution of red snow algae in and around Gulkana Glacier, Alaska
Keywords:Snow, Glaicer, Alaska, Red snow, Snow–ice microbes
The phenomenon of red snow observed in arctic region is characterized by the changing of the snow surface from white to red as snowmelt progresses from spring to summer. This phenomenon leads to a decrease in albedo by 0.1–0.2, thereby accelerating snowmelt. Red snow is mainly caused by photosynthetic microorganisms known as snow algae. While red snow has been reported in the snow on glaciers, soil, and vegetation in high-altitude regions, however, the conditions driving its occurrence remain unclear. This study aimed to reveal the impact of environmental differences beneath the snow cover on the occurrence of red snow by analyzing the distribution of snow algae and nutrients in red snow collected from the glaciers to the glacier surface to the glacier forefield.
Red snow samples were collected from the Gulkana Glacier in Alaska, USA, from July 3rd to 5th, 2023. Red snow patches were observed in the glacier forefield (elevation 1122–1283 m), while widespread across the glacier surface (elevation 1351–1777 m). The samples, brought back to Chiba University, were observed for microscopic observation, including a description of the morphological characteristics of algae and a calculation of the cell concentration. Additionally, the diameter of algal cells was measured using image processing software (Image J). The major dissolved chemical solutes and dissolved organic nitrogen (DON) in the snow samples were measured as environmental conditions.
The microscopic observation revealed spherical algal cells, which were mainly dominant, but oval, elliptical, and rugby ball-shaped algal cells were also observed. While the cell concentration of spherical algal cells on the red snow surface showed no significant variation from the upper part of the glacier to the glacier forefield (2.6 ± 1.2 × 105 cells mL-1), that of non-spherical algal cells was higher from the lower part of the glacier to the glacier forefield (3.2 ± 2.4 × 104 cells mL-1), with minimal presence in the glacier upstream (2.2 ± 3.0 × 102 cells mL-1). Moreover, the diameter of spherical algal cells was larger in the glacier forefield (19.9 ± 3.9 μm) compared to the glacier surface (13.8 ± 2.6 μm). These findings suggest that the increase in the size of spherical algal cells and the growth of non-spherical algal cells occur regardless of conditions under the snow and are associated with the progression of snowmelt. The absence of nutrients essential for algae, such as PO43-, NO3-, and NH4+, in red snow, along with the high concentration of DON on the glacier surface, implies that DON is decomposed by microorganisms during snowmelt, providing NO3- and NH4+ to red snow algae. From the results, this study suggests that the activity of algal cells in red snow could be limited by the amount of inorganic nitrogen supplied by microbial activity regardless of the environmental conditions under the snow.
Red snow samples were collected from the Gulkana Glacier in Alaska, USA, from July 3rd to 5th, 2023. Red snow patches were observed in the glacier forefield (elevation 1122–1283 m), while widespread across the glacier surface (elevation 1351–1777 m). The samples, brought back to Chiba University, were observed for microscopic observation, including a description of the morphological characteristics of algae and a calculation of the cell concentration. Additionally, the diameter of algal cells was measured using image processing software (Image J). The major dissolved chemical solutes and dissolved organic nitrogen (DON) in the snow samples were measured as environmental conditions.
The microscopic observation revealed spherical algal cells, which were mainly dominant, but oval, elliptical, and rugby ball-shaped algal cells were also observed. While the cell concentration of spherical algal cells on the red snow surface showed no significant variation from the upper part of the glacier to the glacier forefield (2.6 ± 1.2 × 105 cells mL-1), that of non-spherical algal cells was higher from the lower part of the glacier to the glacier forefield (3.2 ± 2.4 × 104 cells mL-1), with minimal presence in the glacier upstream (2.2 ± 3.0 × 102 cells mL-1). Moreover, the diameter of spherical algal cells was larger in the glacier forefield (19.9 ± 3.9 μm) compared to the glacier surface (13.8 ± 2.6 μm). These findings suggest that the increase in the size of spherical algal cells and the growth of non-spherical algal cells occur regardless of conditions under the snow and are associated with the progression of snowmelt. The absence of nutrients essential for algae, such as PO43-, NO3-, and NH4+, in red snow, along with the high concentration of DON on the glacier surface, implies that DON is decomposed by microorganisms during snowmelt, providing NO3- and NH4+ to red snow algae. From the results, this study suggests that the activity of algal cells in red snow could be limited by the amount of inorganic nitrogen supplied by microbial activity regardless of the environmental conditions under the snow.