Algae bloom in snow increasing, how does it impact mountains?

A team of researchers from Chiba University in Japan has recently studied the growth of snow algae blooms on Mount Gassan during the spring season. The researchers collected and analyzed snow samples from different elevations along the mountain to understand how the algae grows.

They discovered that the algal growth begins in the lower forested areas and spreads to the upper alpine zone as temperatures rise, which is closely linked to the phenology of springtime vegetation and trees.

The research, which was published in the journal Arctic, Antarctic, and Alpine Research, provides insights into the growth and spread of snow algal blooms in the mountainous areas of Japan.

Japanese researchers study snow algae

The rise in global temperatures has resulted in the growth of algal blooms in various locations, including water bodies, coastal regions, and mountainous areas, even as far as the Arctic. This has become a cause for concern due to the impact it has on the melting of snow-covered surfaces.

The presence of pigmented snow algae on Mount Gassan after the winter season is particularly worrying as it reduces the reflectivity of the snow, leading to faster melting. Additionally, the algal blooms can have unforeseen effects on the surrounding wildlife and vegetation.

The appearance and growth of snow algae in mountainous regions appear to differ depending on the season, elevation, and predominant vegetation. However, there is still limited information on the occurrence of algal blooms in mountainous areas in Japan.

Nozomu Takeuchi, a Professor in the Department of Earth Sciences at Chiba University, Japan, has taken an interest in the appearance of snow algal blooms on Mount Gassan.

With decades of experience studying organisms in snowpacks and glaciers globally, Takeuchi and his colleague Suzuki Takumi documented the growth and composition of the blooms at various elevations on the mountain.

Takeuchi notes that although Japan experiences high levels of snowfall, little is known about the presence of such organisms in snowpacks. The study aims to increase awareness of the valuable ecosystems found in Japan's mountains.

Season and altitude affect algal blooms

The snow algal blooms on Mount Gassan tend to emerge between late March and early July, following the winter season as the snow begins to melt. The research team collected colored snow samples from seven different locations on the mountain during this period, covering a range of altitudes from 780 to 1656 meters above sea level. These locations included heavily forested areas at lower elevations and alpine grasslands at higher altitudes.

The influence of both season and altitude on the algal blooms was apparent during the sampling phase. In May, green-coloured snow was predominantly found at lower elevations (780-1016 m above sea level).

By June, the green-coloured snow was observed further up the mountain, and patches of red-colored snow were found at the highest survey location, at 1656 m above sea level.

In July, the number of red-coloured snow patches had increased, indicating that the algal blooms had multiplied. This trend implies that the growth of snow algae begins in lower forested areas and expands to upper alpine zones as temperatures increase during the season.

Chlorophyll analysis conducted in the laboratory confirmed the researchers' observations, demonstrating that chlorophyll-a concentration in the snow samples collected from various sampling sites had risen from May to July.

Understanding algal blooms in mountains

The researchers delved into the reasons behind this phenomenon by examining the snow samples for soluble chemical ions. Their investigation disclosed that the concentration of algal blooms was linked to the presence of nutrients that promote their growth, such as phosphate (PO43−), ammonium (NH4+), and potassium (K+).

These nutrients were traced back to plant litter, particularly shed bud scales, which were detected on the snow surface during sample collection. Shed bud scales are a common occurrence during the budburst of deciduous trees, a natural process whereby scales protecting the buds during winter are shed and fall to the ground in the spring and summer months. Satellite images of the tree cover confirmed this, revealing the expansion of the forested areas of the mountain from May to July.

Professor Takeuchi speaking to Groundreport.in said that their research discovered that snow algal blooms thrive in various elevations, from lower forested areas to the upper alpine zone during the melting season and that the emergence of these blooms is closely linked to springtime vegetation and tree phenology.

"Given the rise in global temperatures, the prevalence of algal blooms in mountainous regions is expected to increase. Thus, understanding the growth and spread of these blooms is crucial to building resilience against climate change" he added.

He added, "the knowledge is also essential in predicting and mitigating the impacts of global warming on vulnerable ecosystems such as the cryosphere and associated wildlife not only in Japan but also worldwide".

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