The Microscopic Life of Glaciers

Svalbard Glacier, courtesy of Airflore/Flickr.
Svalbard Glacier, courtesy of Airflore/Flickr.

Though it can be hard to imagine that cold, barren-looking glaciers are conducive to life, glaciers are actually teeming with organisms. Glacier surfaces are filled with cylindrical holes called cyroconite holes, in which melt water accumulates and micro-algae and cyanobacteria  thrive.

Now, a new study published in Biogeosciences has taken a closer look at these complex ecosystems to better understand the interactions between the organisms that inhabit this icy space. They found that Svalbard glaciers that received large quantities of deposits from local areas tended to have large amounts of microalgae. These microalgae can create large colonies to protect them from invertebrate grazers like tardigrades, minute animals also known as water bears, and other microscopic animals like rotifers and ciliates. Large microalgae colonies can protect themselves from the filtration feeding strategy used by rotifers.

The researchers studied these mini-ecosystems on four glaciers in Svalbard, a Norwegian Archipelago. Each sample had a different level of exposure to nutrients, water depth and the degree to which the cyroconite holes were isolated so that the researchers could separately analyze the effects of environmental factors and other biological interactions, such as animals grazing on the microalgae.

Under a microscope, the researchers identified the different species of tardigrades and rotifers. They also measured the density of microalgae clusters and the types of microalgae and cyanobacteria.

Colony of rotifers, courtesy of Specious Reasons/Flickr
Colony of rotifers, courtesy of Specious Reasons/Flickr

In glaciers farther away from glacier-free land, the microalgae species differed from glaciers closer to land. Species variability could be attributed to wind transport, the researchers suggest.

“We propose that selection occurs because polar cyanobacteria are often associated with dust in soil, and thus easily transported by 20 wind,” they wrote. Levels of nitrogen deposits from bird guano and tundra may also play a role in determining which species of microalgae lived where, but the researchers felt this factor was less important than wind transportation.

The species and quantities of grazers, on the other hand, did not vary much from site to site. Grazer types were also correlated with the types of microalgae found in different cyroconite holes. Rotifers tended to live around Zygnemales and Chlorococcales, while tardigrades were usually found around larger Zygnemales.

“The high abundances of tardigrades, rotifers, and ciliates, including genera with different feeding strategies, have been found and suggest a complex food web between more trophic levels than measured in the present study,” the authors wrote. “Feeding experiments and analysis of stomach contents may help to bring a more detailed picture of this yet hardly known food web.”

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Roundup: Grounding Lines, Fault Lines and Algae-filled Pits

NASA reports on the Hidden Melting of Greenland’s Glaciers

“What’s causing this ‘big thaw’? Rignot’s team found that Greenland’s glaciers flowing into the ocean are grounded deeper below sea level than previously measured. This means that the warm ocean currents at depth can sweep across the glacier faces and erode them.“In polar regions, the upper layers of ocean water are cold and fresh,” he explains. “Cold water is less effective at melting ice. The real ocean heat is at a depth of 350-400 meters and below. This warm, salty water is of subtropical origin and melts the ice much more rapidly.”

To learn more, click here.

Biological interactions between Microalgae and Glacial Grazers

Microalgae
Microalgae. Photo courtesy of Wikipedia.

“Glaciers are known to harbor surprisingly complex ecosystems. On their surface, distinct cylindrical holes filled with meltwater and sediments are considered as hot spots for microbial life. The present paper addresses possible biological interactions within 5 the community of prokaryotic cyanobacteria and eukaryotic microalgae (microalgae) and relations to their potential grazers, additional to their environmental controls…. We propose that, for the studied glaciers, nutrient levels related to recycling of limiting nutrients is the main factor driving variation in the community structure of microalgae and grazers.”

Read more about the study here.

Italy’s glaciers retreated by 40 percent: WWF

Matterhorn glacier
Courtesy of Wikipedia

“ROME: Alpine glaciers in Italy have lost an estimated 40 percent of their area over the last three decades, a recent report released by World Wildlife Fund (WWF) has said.
“The situation of glaciers on the Italian side of the Alps is very worrying,” Xinhua news agency on Friday quoted Gianfranco Bologna, scientific director of WWF-Italy and co-author of the report as saying. The Hot Ice report was unveiled earlier this week, ahead of a crucial United Nations Climate Change Conference due to be held in Paris from November 30 to December 11.”

Read more here.

 

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