A first global atlas of the bacterial microbiome in the world’s glacier-fed streams

Glaciers and their streams are vanishing at an unprecedented pace because of global warming. What else are we potentially losing beside freshwater resources? In our article in Nature, we show what else besides freshwater resources we are potentially losing as glaciers shrink — a unique microbiome!
Like

Share this post

Choose a social network to share with, or copy the URL to share elsewhere

This is a representation of how your post may appear on social media. The actual post will vary between social networks

Five years ago, life in the deepest ocean was better understood than the one in the streams that drain the roof of our planet. And so began a scientific journey through uncharted waters to unravel the hidden microbial life in one of Earth’s most extreme ecosystems nurtured by the meltwaters of mountain glaciers.

Over the course of four years, we cruised the peaks of the major mountain ranges in New Zealand, Russian Caucasus, Himalaya, Pamir and Tien Shan, Africa, Europe, Alaska, Greenland, Ecuador and Chile. In an unprecedented effort, we sampled a total of 170 glacier-fed streams, shipping back to our lab at the Ecole Polytechnique Fédérale in Lausanne, Switzerland, thousands of samples of benthic sediment and streamwater. Alongside microbial samples, we also captured complementary data related to streamwater chemistry, glacier properties and geography.

A multidisciplinary and international team, blending expertise from microbial ecology, molecular biology, biogeochemistry, geology and glaciology studied the precious samples, and now present a first global atlas of the bacterial microbiome in glacier-fed streams.

Why we think our work is exciting

What makes this works so exciting? The disappearance of glaciers and vanishing of their streams are emblematic of climate change. Studying the bacterial microbiome of glacier-fed streams, we found that its structure and function differ from other cryospheric microbiomes. This means, it is quite distinct among its icy cousins.

As ice melts, water is cold. It is also extremely poor in resources, such as organic carbon and inorganic nutrients. Because of the high elevation, glacier-fed streams are typically dark throughout winter, covered underneath ice and snow. In summer, ultraviolet radiation can be high. So, the extreme environment of glacier-fed streams is fairly similar, admittedly with some exceptions, around the world. Studying a catalogue of more than 50,000 Amplicon Sequence Variants (ASVs), we found the glacier-fed stream microbiome exhibits an unexpected diversity. Marked spatial patterns emerged from our data, with marked differences in microbiome composition across mountain ranges and between hemispheres. Even more exciting is the fact that more than half of the bacterial ASVs are specific to a given mountain range, with the highest levels of specificity found in New Zealand and the Ecuadorian volcanoes. This is reminiscent of the endemicity of plants and animals on these ‘islands’. Furthermore, and quite surprising, we found numerous bacteria to be even unique to a single stream!

What drives these spatial patterns? Our findings suggest that it is the geographic isolation at the mountain peaks and the selective environment that drive the observed biogeography. While this is a cool finding science-wise, it may be less given what lies ahead. ‘Endemic’ species are highly prone to extinction, and that is what our work suggests given the uniqueness of the GFS microbiome and the rapid pace at which the GFS environment is changing.

Once thought eternal, the immaculate snow-capped and frozen giants are vanishing. With this, we are potentially losing a hitherto unseen microbial biodiversity where liquid water starts to flow down Earth’s heights. While this microbial life is invisible to the naked eye, it does support the biodiversity of plants and animals that we all appreciate so much.

The long and hard way to the peaks and back to the lab

Cruising our planet’s roof is not like cruising oceans. It is bumpier. The journey to reach 170 glacier-fed streams was paved with a heavy dose of strategic planning, contemplated by immense physical efforts, psychological challenges and bureaucratic hurdles. Ascending mountains through snow storms, looking for shelter under the blazing tropical sun, having feet in the mud literally flowing down the steep slopes of the Rwenzori Mountains, or simply waiting for hours in the cold for in situ incubations, comprised the mosaic of this tour de force.

In the most extreme moments, the physical load turned into psychological stress when the team had spent up to four months exposed in high-altitude terrain during the Nepalese Himalaya and Pamir-Tien Shan back-to-back expeditions. 

The Covid pandemic was another spicy experience adding to this logistical, physical and mental load. The uncertainty of an upcoming lockdown, perhaps even a new variant against which our vaccination would provide poor protection was nerve-racking and always spinning in the back of our heads. During the pandemic time, we devoted ourselves to an endless testing of porters and mountain guides, repeated every time before we hit the road to encounter the glaciated giants in Nepal, Kyrgyzstan and Uganda. The cherry on the pandemic pie was the team’s lockdown in Kathmandu with no way to escape the deserted city.

Obviously, we were not alone along this scientific mountaineering journey. Without more than 100 brave men and women, porters, guides, students and scientists our expeditions would not have been possible. Our porters carried up hundreds of kilograms of scientific material, camping gear and food. The great attraction was our containers meticulously filled with liquid nitrogen and precious samples in deep frozen state — weighing up to 45 kg. Too often did we follow discussions and witnessed jealousy among porters as for who is privileged to carry that ‘monster’, even up to 5000 meters above sea level in precarious alpine terrain. We are so grateful to all these outstanding people for their engagement as these encounters have been true eye opener for us and have forged new friendships.

This unprecedented effort of first cruising Earth’s heights and then the depth of the sequences would not have been possible without the support of The NOMIS Foundation, for which we are most grateful.

Please sign in or register for FREE

If you are a registered user on Research Communities by Springer Nature, please sign in

Follow the Topic

Bacteria
Life Sciences > Biological Sciences > Microbiology > Bacteria
Earth Sciences
Physical Sciences > Earth and Environmental Sciences > Earth Sciences
Microbiome
Life Sciences > Biological Sciences > Microbiology > Microbial Communities > Microbiome
  • Nature Nature

    A weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions.