Discovery highlights potential for life on Mars, global climate change in Arctic

A new study published by Colorado State University researchers has found that bacteria and fungi not only survive but actively grow in the frozen Arctic tundra — a discovery that has significant implications for life on cold planets such as Mars and for how Arctic soils respond to global climate change. In recent years, scientists have discovered viable bacteria and other microscopic organisms in some of the most extreme cold environments on Earth. They have been able to isolate some of these microorganisms and grow them under laboratory conditions.

"We know that microorganisms living in permanently frozen environments may have had thousands of years to adapt to those conditions, but what about microorganisms that live in environments that are only frozen for part of the year, such as the Arctic tundra soil?" posits Shawna McMahon, co-author of the study and post-doctoral researcher in CSU's Natural Resource Ecology Laboratory, or NREL. "Are these microorganisms able to perform cellular maintenance or grow under frozen conditions?"

Tundra microorganisms experience relative warm conditions in the summer, but the researchers are interested in how the microorganisms grow in frozen winter conditions.

"We were able to definitively show for the first time that both bacteria and fungi are not only surviving the Arctic winter, but some of them are actively growing in the frozen Arctic tundra soil," says Matt Wallenstein, NREL research scientist and study co-author.

The implications of this discovery are far-reaching. Evidence of frozen water on Mars has fueled speculation that life could have evolved on other planets. But Mars has been frozen for billions of years, explains McMahon. "Based on our findings, bacteria and fungi are capable of actively growing below freezing temperatures, which suggests that if life did evolve on Mars, bacteria and fungi could have persisted despite frozen conditions."

Beyond the potential of life on Mars, this discovery may help scientists further understand the effects of global climate change on Arctic soils. Some scientists are concerned that global warming may melt permafrost and increase the length of summer in the Arctic. Longer summers may result in the decomposition of currently frozen soil carbon, increasing the release of carbon dioxide into the atmosphere.

"Our results suggest that longer Arctic summers may not be the only important aspect of climate change. Milder winters may also play a role in contributing more carbon dioxide into the atmosphere," says Wallenstein.

McMahon and Wallenstein worked with Josh Schimel from the University of California-Santa Barbara on this study, which was funded by the National Science Foundation. The researchers collected and studied Arctic tundra soil samples from the Toolik Lake region in Alaska.

The study was published in the March issue of Environmental Microbiology Reports.

Wildlife has declined markedly in Kenya’s prized national reserve

Populations of wild grazing animals in Kenya's treasured Masai Mara National Reserve have decreased substantially in only 15 years as they compete for survival with the growing human settlements in the region, say researchers at Colorado State University and International Livestock Research Institute, or ILRI.

Six species — giraffes, hartebeest, impala, warthogs, topis, and waterbuck — declined markedly and persistently throughout the reserve, the scientists found.

The study, used by the Nairobi-based ILRI and funded by World Wide Fund for Nature, is based on rigorous, monthly monitoring between 1989 and 2003 of seven ungulate, or hoofed, species in the Masai Mara National Reserve, which covers some 1,500 square kilometers in southwestern Kenya.

Robin Reid, director of the CSU Center for Collaborative Conservation, co-authored the study, which provides the most detailed evidence to date on declines in the ungulate populations in the Mara and links the phenomenon to the rapid expansion of human populations near the boundaries of the reserve.

The growing human population has diminished the wild animal population by usurping wildlife grazing territory for crop and livestock production to support their families. Monthly sample counts indicate that the losses were as high as 95 percent for giraffes, 80 percent for warthogs, 76 percent for hartebeest, and 67 percent for impala.

"The situation we documented paints a bleak picture and requires urgent and decisive action if we want to save this treasure from disaster," says Joseph Ogutu, lead study author and a statistical ecologist at ILRI. "Our study offers the best evidence to date that wildlife losses in the reserve are widespread and substantial, and that these trends are likely linked to the steady increase in human settlements on lands adjacent to the reserve."

The research was published in the May 2009 issue of the British Journal of Zoology. Access the full report at http://tinyurl.com/Ogutumarastudy.