RESEARCH NEWS STORYTokyo, April 19, 2023
Chiba University
Investigating the Growth of Snow Algal Blooms on Mount Gassan, JapanThe findings highlight vegetation’s influence on the color and occurrence of snow algal
blooms and the presence of vulnerable ecosystems
Snow algae blooms have recently been observed on the slopes of Mount Gassan in Japan
during the spring season. To understand their growth, researchers from Chiba University
collected and analyzed snow samples from different elevations along the mountain. They
found that algal growth begins in the lower forested areas and spreads to the upper alpine
zone as the seasons get warmer, and this is closely tied to springtime vegetation and tree
phenology.

Image: Algal blooms on Mount Gassan have a strong association with springtime vegetation and tree phenology
Caption: Algal blooms appear on Mount Gassan (top left) during the spring season when the snow begins to melt.
Pictured at the top right, and bottom left and right are the yellow, green, and red colored algal blooms that wereobserved at the lower forest sites and the higher alpine areas, respectively.

Rising temperatures have led to the growth of algal blooms in water bodies, mountainous
areas, and coastal regions as far as the Arctic. Recently, pigmented snow algae have beenspotted on Japan’s Mount Gassan after the winter season. The presence of such algal blooms
is concerning because they reduce the reflectivity of snow-covered surfaces, resulting infaster snow melting. Additionally, the algal blooms can have unforeseen impacts on thesurrounding wildlife and vegetation. The growth and color of snow algae in mountainous
areas appear to differ depending on the season, elevation, and predominant vegetation.
However, there is limited information on the appearance of algal blooms in the mountainous
areas in Japan.
The appearance of snow algal blooms on Mount Gassan caught the attention of Nozomu
Takeuchi, a Professor in the Department of Earth Sciences at Chiba University, Japan, who has
decades of experience studying organisms in snowpacks and glaciers around the world.
Together with Suzuki Takumi from the same faculty, Prof. Takeuchi documented the growthand composition of such blooms at different elevations on Mount Gassan. Their findings,
which were published in Volume 55 Issue 1 of the journal Arctic, Antarctic, and Alpine
Research, on March 13, 2023, shed light on the growth and spread of snow algal blooms inthe mountainous regions of Japan.
“Although Japan has exceptionally high levels of snowfall, the presence of such organisms
living in snowpacks remains unknown. This study may induce people to acknowledge theprecious ecosystems in the mountains of Japan,” says Prof. Takeuchi, explaining themotivation behind their study.
The algal blooms in Mount Gassan typically appear from late March to early-July, which isafter the winter season when the snow starts to melt. During this period, the researchers
collected colored snow samples at seven different locations on Mount Gassan. The locations
spanned a range of altitudes, from 780 to 1656 meters above sea level (a.s.l), encompassing
heavily forested areas at lower altitudes and alpine grasslands at higher elevations.
The effects of both season and altitude on algal blooms became quickly apparent during thesampling phase. In May, the researchers observed mostly green-colored snow at lowerelevation sites (780-1016 m a.s.l). In June, the green-colored snow was found further up themountain, and patches of red-colored snow were found at the highest survey location, at anelevation of 1656 m a.s.l. By July, the algal blooms on this site had multiplied, resulting in theresearchers finding numerous patches of red-colored snow. This trend indicates that algal
growth begins in the lower forested areas and spreads to the upper alpine zone as the seasons
get warmer. Their observation was confirmed by laboratory chlorophyll analysis, which
revealed that chlorophyll-a concentration in the snow samples collected across the different
sampling sites increased from May to July.
To find out why this happens, the researchers analyzed the snow samples for soluble chemicalions. Their findings revealed that the concentration of algal blooms corresponded with thepresence of nutrients associated with the growth of algal blooms, such as phosphate (PO43−),
ammonium (NH4+), and potassium (K+), which were found to originate from plant litter,particularly shed bud scales that were noticed on the snow surface during sample collection.
These shed bud scales are a common occurrence during the budburst of deciduous trees, aphenomenon wherein the scales that protect the buds during winter are shed and fall to theground during the spring and summer months. This was confirmed by satellite images of thetree cover, which revealed the expansion of the forested areas of the mountain from May toJuly.
“Our investigations revealed that snow algal blooms develop across the elevational range
from the lower forested areas to the upper alpine zone during the melting season, and thatthe emergence of algal blooms is strongly associated with springtime vegetation and tree
phenology,” explains Prof. Takeuchi.
Warmer global temperatures are likely to make algal blooms more prevalent in the mountains.
Understanding how these blooms grow and spread can help us become more resilient to theeffects of climate change. This is also important for predicting and ameliorating the effects ofglobal warming on vulnerable ecosystems like the cryosphere and associated wildlife in Japanand the rest of the world.
Funding
This work was supported by grants from the JSPS KAKENHI and the Arctic Challenge for
Sustainability II (ArCS II).
About Professor Nozomu Takeuchi
Nozomu Takeuchi has been a professor in the Department of Earth Sciences at Chiba
University in Japan since August 2012. Over the past two decades, he has conducted extensive
research on the ecology of microbes that reside on snow and ice, as well as their physical andbiogeochemical processes on glaciers. He has studied ecosystems in remote locations acrossthe globe, including the Himalayas, Tienshan, Pamir, Altai, Japanese Alps, Alaska, Patagonia,Svalbard, and Greenland. Most recently, in 2017, he was part of a project to investigate theGreenland Ice sheet.
Contact:
Nozomu Takeuchi
Department of Earth Sciences, Graduate School of Science, Chiba University
Email: ntakeuch@faculty.chiba-u.jp
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