Find out more about the world’s oldest and deepest river, Lake Baikal – and why bubbles under its surface threaten to harm the planet
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Holding 23 per cent of the world’s supply of freshwater – more than all of the US’s five Great Lakes combined – Lake Baikal is a leviathan in the watery world. Its depth, too, tops the charts at a staggering 1,642m at its deepest point, equivalent to 17 Big Bens, while its age – an estimated 25-30 million years old – makes it the world’s oldest lake.
This vast lake is situated in the mountainous part of eastern Siberia in Russia, north of the Mongolian border. More than 330 rivers and streams flow into it, including the Chikoy, Uda, Selenga and Bargunzin.
From January to May, Lake Baikal is covered in an ice sheet between 1-2m deep, while across the year, its temperature sits at an average of 4ºC. Despite its reputation as an icy expanse of water, the lake’s surface temperature rises to a balmy 22–23ºC in summer months.
What lives in Lake Baikal?
You might think that the remote location of Lake Baikal makes it inhospitable, but the crescent-shaped body of water is, in fact, home to 1,500–1,800 animal species, as well as hundreds of plant species. There are also more than 320 bird species in the region. Most of these are endemic to Lake Baikal, with their existence useful for researchers to study for evolutionary science.
So rich in biodiversity is the lake that it is often dubbed the ‘Galápagos of Russia’.
Endemic species of Lake Baikal include the semi-transparent pink golomyanka – also known as the Baikal oilfish – which gets its name from the fact almost half of its body consists of fat. The species possesses a gigantic mouth that stretches 1.5 times wider than its body, and is known to consume its siblings at birth.
While the Baikal oilfish is inedible to humans, it is a firm favourite for the Baikal seal (Pusa sibirica), another endemic species to the lake and also the only seal in the world to live in freshwater.
If you want to see some of these creatures yourself – and you’re a keen adventurer, you can even dive in Lake Baikal’s waters in February or March!
In recent years, scientists have expressed concerns over the Baikal seal’s declining population, attributed to the hunting of the species each spring for their meat and to produce seal oil for medicinal purposes. Lax enforcement combined with rising prices for seal fur – particularly from young seals – has also led to an uptick in poaching the animals.
Baikal seals get caught as bycatch in fishing gear and nets – an estimated 1,000 seals die this way each year.
Along with the pressures from hunting, Baikal seals are also threatened by a loss of shoreline habitat as industries and businesses carry out commercial development.
Bubbles under the ice
While Lake Baikal is known for its transparent waters – where objects can be seen up to 130ft (40m) below the surface – there is another fascinating fact about its depths.
Lake Baikal’s water is also home to a strange phenomenon that produces stunning bubbles underneath the water’s surface. These are made from methane – the greenhouse gas – formed after organic matter like plants and animals decay at the lake’s bottom and are fed on by anaerobic bacteria, a process known as methanogenesis.
This methane then becomes bubbles which rise in the water column – a sight that might appear captivating but causes concern to scientists. Methane is around 25 times more effective at trapping heat in the Earth’s atmosphere than carbon dioxide, and as the planet experiences more and more ice melt as a result of climate change, the impact of these methane-filled lakes melting is a serious issue.
Lake Baikal pollution
Around ten to twenty years ago, the waters of Lake Baikal were so pure that they could be consumed by humans without treatment. Now, some parts of the lake are so polluted that tourists are advised not to swim in it. So what exactly is polluting Lake Baikal?
One considerable pollutant tainting the lake is microplastics. A recent study found that in some areas of Lake Baikal, the concentration of microplastic particles is of the same order of magnitude as the concentrations in ocean ‘garbage patches’ – like those in the Pacific which accumulate extreme quantities of plastic waste dangerous to surrounding wildlife and ecosystems.
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The research focused on a particular area of the lake, filtering 1,676 cubic metres of water. In it, scientists found 446 plastic particles, of which 91.6 per cent were microplastics.
Sixty per cent of the particles found in Lake Baikal were thought to be from plastic films, such as those used in food packaging. As well as this, green polypropylene fibres were discovered, which are linked with the debris from fishing nets. Scientists hope that these nets, sunk deep beneath the lake’s surface, can be retrieved to prevent them from shedding plastic long into the future.
Historically, another source of pollution was that coming from a paper mill built on the lake’s shores.
While the Russian government closed the factory back in 2013 following years of complaints over its ecological impact of spewing waste into the lake, there are still reservoirs filled with 6.5 million tonnes of waste sludge produced by the mill, raising concerns about how they will be effectively disposed of.
Increased tourism – good or bad?
A few decades ago, just a few thousand visitors would flock Lake Baikal each year. Now, that number is between three to four million each year – thanks to a rise in domestic tourism and that from nearby Chinese cities – and is seemingly on the rise. While tourism does provide economic benefits to the regions surrounding the lake, it brings about a new wave of pollution risks to consider and tackle.
Weak regulations on building and construction near the lake has led to hotels, stores and other services slowly encroaching near the shores, embarking on projects in the name of tourism that often overlook environmental regulations.
A lack of sewage and water treatment facilities, along with garbage disposal and recycling centres in the area also means that untreated water and waste can enter the lake and further pollute it.
