Microorganisms In Antarctic Dry Valleys Relocating To Counter Thawing Ice

The McMurdo Dry Valleys is one of the most unforgiving environments on Earth. This cold desert does not have much-living beings roaming on the lands. The annual average temperatures hover around 5 F, leaving a vast, icy plains of nothing but permafrost. But the microorganisms that do live there are declining in number, a new study has found.

A 20 year-long study of the soil fauna, nematodes, and other animal species in the McMurdo Dry Valleys have shown that rising climatic conditions since 2001 has led to a decline in the microorganisms in the region.

A research team led by Colorado State University measured soil properties, including water content, in three hydrological basins and at three different elevations in the region. The field study was launched in Taylor Valley in 1993; in Miers and Garwood valleys, scientists started their work in 2011, reported Science Daily.

The region has been witnessing increasing temperatures since 2001. Before that, the annual temperatures were falling steadily. The warming has triggered melting and thawing of ice in this desert.

“Until 2001, the region was not experiencing a warming trend,” Walter Andriuzzi, the lead author of the study and a postdoctoral researcher in the Department of Biology and School of Global Environmental Sustainability, said in a press release.

“On the contrary, it was getting colder,” Andriuzzi said adding, “But in 2001, the cooling trend stopped abruptly with an extremely warm weather event. Since then, the average temperatures are either stable or are increasing slightly. But most importantly, there have been more frequent intense weather events.”

Located in the largest land region of the Antarctic continent, no animals live here. Not even the toughest creatures can brave the year-long freezing temperatures and frozen Earth. Only microscopic soil invertebrates live in under the frozen rocks here.

On studying these soil invertebrates, studying the water content found a downward trend in the number of microorganisms they found in the soil samples. The amount of ice thawing in the region has increased in the last 10 years. This increase in average temperatures was found to be the major cause of death of the soil organisms.

“It’s a few hours or days of unusually warm weather,” Andriuzzi said. “There are even peaks of high solar radiation that trigger ice thawing without high temperatures. That’s how climate change is happening there, and it’s already starting to impact the biological community there.”

The researchers also found that the most common species that they usually find in the region like the nematode Scottnema lindsayae and several other species were seen migrating towards the colder regions to avoid the warming rocks down below. This was causing a higher diversity of microorganisms in the soil at higher altitudes.

The researchers say that these changes will impact the ecosystem in ways they cannot predict but will have to wait and see. “It’s easier in places like the dry valleys to isolate the effects of climate change, or to isolate how one species respond to climate change in one way,” Andriuzzi said. “It’s a natural laboratory, where some of the mechanisms that operate elsewhere can be unveiled.”

According to the team, the changes in this regions are just mirroring changes worldwide. But, here the changes are microscopic and easier to read. The researchers state the example of the Rocky Mountains where insects have been documented moving uphill on a year to year basis, due to warming temperatures like a migration—a behavior never observed in the region before.

According to Andriuzzi, it is amazing how these “remarkable creatures” survive in such harsh cold. The rising temperatures only last a few weeks but the 10-year lifespan of these microorganisms is cut-short.

“With climate change, some species are winners, some are losers,” he said. “In the Dry Valleys, it’s all about how they respond to warming and, most importantly, water."