Toxic algae invade Russia's Lake Baikal

Yury Azhichakov, a retired ecological engineer, set out early by bike for Senogda Bay, his favourite beach, on the northwestern shore of Lake Baikal in Siberia, Russia.

The world’s oldest, deepest and most voluminous lake, Baikal holds 20% of the planet’s unfrozen freshwater. It is often described as the world’s cleanest lake. As Yury discovered, that is no longer the case. Senogda’s once pristine sands were buried under thick mats of reeking greenish-black goo.

The muck, scientists have discovered, follows mass algal blooms at dozens of sites around Lake Baikal’s 1,240-mile perimeter. Confined to shallow water and shores near towns and villages, the problem seems to stem from an influx of untreated sewage — the result of inadequate wastewater treatment. Algal blooms threaten iconic freshwater bodies around the world. But Lake Baikal is especially precious: a World
Heritage site home to more than 3,700 species, more than half found nowhere else.

Extensive damage

“People are dumping sewage, waste and rubbish around the lake, creating pretty appalling conditions in some places,” said Anson MacKay, an environmental scientist at University College London, United Kingdom. Runoff from fertilisers and other pollutants leads to so-called eutrophication, an excessive growth of algae. These blooms eventually deplete the water of oxygen, suffocating aquatic plants and animals.

Russian scientists had assumed that Lake Baikal is simply too vast to suffer such a fate, but recent growth in tourism and development seem to be changing the calculus. “We have a saying in Russia: A clever person is trained on the mistakes of others,” said Oleg Timoshkin, a biologist at the Russian Academy of Science’s Limnological Institute in Irkutsk, 40 miles from Baikal’s southwestern shore. “Unfortunately, we’re now repeating the mistakes of so many other countries.”

Oleg and his colleagues have found that Spirogyra, a type of green algae that had rarely grown in Lake Baikal’s shallow zones, accounts for the outbreaks. In Severobaikalsk, the researchers traced Spirogyra blooms to locations downstream of the town’s wastewater facility, as well as to an illegal sewage dumping site.

The researchers also found little difference in phosphorus and nitrogen content in treated and untreated water entering the lake. And, as it turned out, Russian Railways had been adding industrial-grade waste to the town’s sewage system, overwhelming it. Despite remedial action, high levels of phosphorus and nitrogen in Severobaikalsk’s wastewater persist even today, and fecal bacteria in treated wastewater have turned up at various sites around Lake Baikal. Oleg’s team is trying to figure out which nutrients are fueling Spirogyra’s growth.

Intervention is vital

Spirogyra smothers other species of algae, and thousands of empty snail shells regularly wash up alongside the blooms. But the damage is more extensive. Underwater forests of native Lake Baikal sponges have begun dying off. In nearly 90 dives around the lake, researchers have found that 30 to 100% of sponges are affected in a given area. The cause of death is unknown,
although Oleg and his colleagues suspect that pathogens from sewage may be
causing disease outbreaks, or that the influx of nutrients is causing symbiotic algae to vacate the sponges. Without intervention, the researchers believe that the environmental damage will worsen.

Earlier this year, Oleg and his colleagues also published their findings in The Journal of Great Lakes Research. They are calling for an immediate ban on synthetic detergents and for help from the federal government in reforming sewage facilities around the lake. But such fixes will probably be slow to come. Some government officials and academics insist that the problems are caused by climate change, not pollution.

Russia’s Ministry of Natural Resources and the Environment has yet to formally acknowledge that the lake’s health is in question at all. “One of the tragedies of Baikal is that top-level, senior scientists who are themselves never on a field expedition mistakenly believe that the lake can never be eutrophied because it is too huge, too pure and full of too much water,” Oleg said. “It’s an easy idea to have, but it’s wrong.”

Eutrophication, however, is not the only threat to Lake Baikal. Mongolia is planning to build up to eight hydroelectric dams on  River Selenga and its tributaries, the source of 50% of Lake Baikal’s surface water. Despite hearings and protests in Russia and Mongolia, the Mongolian government argues that the dams will help achieve energy independence. Researchers predict that Mongolia’s dams would have significant ecological effects on Lake Baikal, including disrupting the flow of water and sediment into the lake, effecting the quality of breeding sites for birds and fish, and blocking migration routes.

Heeding such warnings, China, which is funding the largest of the projects, froze all dam construction until Mongolia and Russia jointly assess potential effects. “This is important, but just a small step in the right direction,” Eugene Simonov, an international coordinator with the nonprofit Rivers Without Boundaries Coalition said.