- A first-of-its-kind expedition in 2019 attempted to map the biodiversity on Mount Everest by using environmental DNA, or eDNA.
- With eDNA, the team was able to detect species that would have been hard to observe visually.
- The findings aim to serve as baseline data for future expeditions that study how climate change is reshaping life on the world’s highest peak.
It’s tough enough to study one particular species endemic to Sagarmatha, the Nepali name for Mount Everest. Imagine attempting to catalog the entire wealth of biodiversity that makes its home on the world’s highest mountain. That’s the gargantuan task that Tracie Seimon set out to do when she led a team that was part of a first-of-its-kind expedition to the mountain in 2019.
Over four weeks, working with the nosebleed peaks of the Himalayas towering around them, Seimon and her team collected 20 liters (5.3 gallons) of water from ponds and streams on and around Sagarmatha. (The team worked on the mountain’s southern flank, which lies in Nepal; the northern flank is in Tibet, China, where the mountain is known as Qomolangma.) Once back at their labs in North America, they searched the water for environmental DNA, or eDNA — trace amounts of genetic material shed by living organisms — to conduct a biodiversity assessment. What they found was far more than they had expected.
The team identified DNA from organisms belonging to 187 taxonomic orders, which constitutes 16.3% of the total known orders.
“Mount Everest and the landmass above 4,500 meters [14,700 feet] only occupies less than 3% of global landmass,” Seimon, director of the molecular diagnostics laboratory at the Wildlife Conservation Society (WCS), told Mongabay in a video interview. “We were really surprised to find 16% of global orders above this elevation.” WCS partnered with National Geographic and Appalachian State University for the expedition.
For example, Seimon and her team found DNA evidence of Tibetan snowcock (Tetraogallus tibetanus), a species of bird notorious for being difficult to spot because of how well it blends into its surroundings. They also detected microscopic animals like rotifers (Rotifera) and tardigrades (Tardigrada), which are known to be able to withstand harsh environments. Seimon’s team was also surprised by the presence of domesticated chicken in the samples, probably indicative of the presence of humans who hike the mountain.
“It gave us a good snapshot of the biodiversity that’s up there at this particular point in time,” Seimon says.
eDNA uses genetic material that has been shed in soil or water, such as from fur, saliva or droppings, to identify organisms and better understand entire ecosystems. The tool has been gaining prominence in recent years because of its non-invasive nature, ease of access, and ability to survey large environments.
Researchers say the data will serve as a baseline to compare how the melting of glaciers, accelerated by global warming, are reshaping life on Everest. Several of the detected organisms can be used as indicator species — one whose presence can indicate a healthy ecosystem, and which, like the proverbial canary in the coal mine, are susceptible to disturbances in the environment.
Mayflies (Ephemeroptera), for instance, were detected across several sites. These aquatic insects are very sensitive to changes in water quality, making their presence indicative of a healthy ecosystem. Seimon’s team is now mapping the distribution of mayflies in an attempt to monitor how water pollution and climate change alters their presence over time.
Seimon says more expeditions are required in the future to monitor how global warming is impacting the ecosystem. “Our question was simply, ‘Can we actually apply eDNA to study biodiversity on Everest?’” Seimon says.
Now, with proof of concept established, Seimon says, it’s imperative to approach the collection and analysis of samples while keeping the limitations of eDNA in mind.
“Just because you find it with eDNA doesn’t mean that it’s necessarily a live organism. It could be an organism that’s shedding dead cells,” she says. “Or, if you have a negative, it could simply be because you just didn’t collect enough water samples.”
Future missions, she says, should use eDNA to dive deeper and get answers to more specific questions about life at the roof of the world.
Seimon points to her previous work monitoring how climate change is impacting amphibian populations in high alpine environments as an example. In the Andes of South America, Seimon found global warming was causing entire ecosystems to move up to higher elevations. As glaciers retreat, they leave new ponds at higher altitudes, prompting amphibians to expand their range higher to occupy those ponds. Once this happens, the ponds start developing algae that form food for the amphibians. Insects then follow.
“The whole biosphere is rising,” Seimon says. But upward-moving ecosystems can reach a breaking point when there’s nowhere higher to go. Meanwhile, “lower down, other species are coming in to compete and that could potentially result in local extinction of those species.”
These are some of the examples from the Andes that Seimon thinks could be translated to the Himalayas as well.
“One could go back, reassess eDNA and see how it changes over time,” Seimon says.
Lim, M. C., Seimon, A., Nightingale, B., Xu, C. C., Halloy, S. R., Solon, A. J., … Seimon, T. A. (2022). Estimating biodiversity across the tree of life on Mount Everest’s southern flank with environmental DNA. iScience, 25(9), 104848. doi:10.1016/j.isci.2022.104848
Seimon, T. A., Seimon, A., Daszak, P., Halloy, S. R., Schloegel, L. M., Aguilar, C. A., … Simmons, J. (2007). Upward range extension of andean anurans and chytridiomycosis to extreme elevations in response to tropical deglaciation. Global Change Biology, 13(1), 288-299. doi:10.1111/j.1365-2486.2006.01278.x