Quantcast

Wildlife Under Siege at the World’s Oldest Lake

Animals
Lake Baikal. W0zny / Wikimedia / CC BY-SA 3.0

By Marlene Cimons

Lake Baikal is the world's oldest and deepest lake. It's at least 20 million years old, and roughly a mile deep at its lowest point. The Siberian lake contains holds more water than all the North American Great Lakes combined, what amounts to more than one-fifth of all the water found in lakes, swamps and rivers. It was formed by the shifting of tectonic plates, which created a valley that filled with water. That shift continues today at a rate of around 1 to 2 centimeters year, meaning the world's biggest lake is only getting bigger.


What's more, Lake Baikal—the name means "nature lake" in Mongolian—is rich in oxygen from top to bottom, meaning life can thrive in its furthest depths. In most deep lakes, the lower waters are absent of oxygen. The surfeit of oxygen helps support a rich diversity of life. Most of the species in the lake—often called the "Galapagos of Russia"—are found nowhere else in the world. UNESCO has designated Baikal a World Heritage Site, calling it "the most outstanding example of a freshwater ecosystem," saying "its age and isolation have produced one of the world's richest and most unusual freshwater faunas, which is of exceptional value to evolutionary science."

So it seems especially tragic that Lake Baikal—like many critically important ecosystems around the world—is now under siege from climate change. Its wildlife face increasing dangers from rising temperatures and pollution. In some places, untreated sewage has fed the growth of green algae, which gobble up oxygen, leaving little or none leftover for other marine life.

Aya bay, on the northeastern coast of Lake Baikal. Sergio Tittarini

"These threats interacting together pushes the lake into unknown territory, for which we can only speculate on the outcome," said George Swann, a researcher at the University of Nottingham's school of geography and co-author of a recent study in the journal PLOS ONE that examines the risks climate change poses to the lake.

Climate change has been causing the lake's water temperatures to rise, reducing ice cover, a trend researchers expect to continue. What's not been clear until now is the extent to which these changes have affected diatoms, microscopic algae that sit at the base of the food chain and help uphold the ecosystem.

A Nerpa seal. Per Harald Olsen

What the researchers found was alarming: diatoms have been declining rapidly as the lake gets warmer. This is bad as these algae provide essential nutrients to other creatures in the water, such as plankton, fish and the world's only freshwater seal, the Nerpa, found only in Lake Baikal. Currently, the Nerpa are safe, but "the potential risk is that as diatoms change, this could, in time, lead to impacts further up the food chain that ultimately impact the Nerpa and their food," Swann said.

The scientists found that other diatoms have been replacing the native diatom species. The invading diatoms, found more commonly in other parts of the world, are lighter and have grow faster. This change is having a ripple effect on the lake, causing a shift in feeding patterns, and possibly the lake's natural cycle of energy and nutrients.

Lake Baikal is located in mountainous Siberia, in southern Russia. Google Maps

"We already see changes in population numbers of different types of zooplankton which eat the algae," Swann said. "We can also speculate that a warmer lake may become more vulnerable to invasive species, several of which, including some aquatic plants, have already gained a foothold in the bays and coastal reaches." The scientists learned about changes in the ecosystem by examining sediment drawn from the lake.

"After death, diatoms sink through the water column with their fossilized remains accumulating alongside other mud at the bottom of the lake," Swann said. "We collected mud that contains these fossils from across the lake, and used a microscope to examine what species were present. By then dating this mud, we can see how the diatom species have changed across Lake Baikal over the last 100 years."

While the entire lake is warming, the decline of native diatoms currently is confined to only one part of the lake, its south basin. Also, while the shoreline of Lake Baikal is suffering from pollution—there already are algae blooms along long stretches of the shoreline—there is no evidence yet that it is hurting diatoms in the deeper open waters.

Frozen Lake Baikal in Irtkutsk, Siberia. Pixabay

"Although climate change is impacting the north basin—for example, seasonal ice is thinning as the lake warms—it is still a very hostile place for the growth of most diatoms, and our data show that only the most specialized species continue to flourish," Swann said. "This may well change in the future."

Moreover, while pollution is abundant enough to worsen water quality along the shoreline, as reaches the further into the lake, it is diluted by clean water. "However, we can't rely on this process continuing in the future," he said. "We know that these shoreline regions can act as early indicators of future widespread change." As pollution accumulates, oxygen-hungry algae may grow in other parts of the lake.

Moreover, the double whammy of pollution and global warming "can often have the same impact," he added. "So both together mean the lake will become stressed from a number of different factors at the same time."

Reposted with permission from our media associate Nexus Media.

EcoWatch Daily Newsletter

Waterloo Bridge during the Extinction Rebellion protest in London. Martin Hearn / Flickr / CC BY 2.0

Money talks. And today it had something to say about the impending global climate crisis.

Read More Show Less
Sam Cooper

By Sam Cooper

Thomas Edison once said, "I'd put my money on the sun and solar energy. What a source of power!"

Read More Show Less
Sponsored

Zero Waste Kitchen Essentials

Simple swaps that cut down on kitchen trash.

Sponsored

By Kayla Robbins

Along with the bathroom, the kitchen is one of the most daunting areas to try and make zero waste.

Read More Show Less
A NOAA research vessel at a Taylor Energy production site in the Gulf of Mexico in September 2018. NOAA

The federal government is looking into the details from the longest running oil spill in U.S. history, and it's looking far worse than the oil rig owner let on, as The New York Times reported.

Read More Show Less
Golde Wallingford submitted this photo of "Pure Joy" to EcoWatch's first photo contest. Golde Wallingford

EcoWatch is pleased to announce our third photo contest!

Read More Show Less
Sponsored
Damage at the Malheur National Wildlife Refuge from the 2016 occupation. USFWS

By Tara Lohan

When armed militants with a grudge against the federal government seized the Malheur National Wildlife Refuge in rural Oregon back in the winter of 2016, I remember avoiding the news coverage. Part of me wanted to know what was happening, but each report I read — as the occupation stretched from days to weeks and the destruction grew — made me so angry it was hard to keep reading.

Read More Show Less
Computer model projection of temperature anomalies across Europe on June 27. Temperature scale in °C. Tropicaltidbits.com

A searing heat wave has begun to spread across Europe, with Germany, France and Belgium experiencing extreme temperatures that are set to continue in the coming days.

Read More Show Less
Skull morphology of hybrid "narluga" whale. Nature / Mikkel Høegh Post

In the 1980s, a Greenlandic subsistence hunter shot and killed a whale with bizarre features unlike any he had ever seen before. He knew something was unique about it, so he left its abnormally large skull on top of his toolshed where it rested until a visiting professor happened upon it a few years later.

Read More Show Less