Bottom of Siberian Lake a Biological Treasure Trove : Science: U.S.-Soviet expedition finds 1,000 unique species in Lake Baikal, many spawned by hot vents.
A joint American-Soviet expedition using a Soviet mini-submarine has uncovered “a living laboratory of evolution” around hot water vents at the bottom of Siberia’s Lake Baikal, providing scientists with an unusual opportunity to study organisms found nowhere else on Earth.
Biological communities around deep-water hot vents have frequently been found in oceans but never in fresh water. The discovery was announced Thursday by the National Geographic Society, which co-sponsored the expedition.
Baikal’s 25-million-year history has allowed it to evolve more than 1,000 species of unique plants and animals, including some such as sponges and seals that are normally found only in salt water.
Hot water vents mark the sites where the Earth’s crust is being pulled apart. The discovery of vents 1,350 feet below the surface at Baikal confirms previous speculation that a similar process is occurring there, said the expedition’s chief scientist, marine geologist Kathleen Crane of Columbia University. “I think this is going to change our interpretation of what is going on in Lake Baikal,” Crane said. “It really is an ocean in the making.”
It is only at these vents that scientists have found the unusual sub-sea communities. Most organisms draw their energy from the sun, either directly, like plants that use sunlight to convert carbon dioxide into sugars, or indirectly, like mammals that eat plants.
But the bottom-dwelling communities draw their energy from hydrogen sulfide released from the vents. Bacteria consume the hydrogen sulfide and use it to form sugars. Other species in the food chain then consume them.
The primary inhabitants of Baikal’s warm water communities were white sponges that grew in circles around the vents. The sponges, Crane said, feed on the bacteria, and then other species feed on them. The researchers observed a variety of other species around the vents, including shrimp and worms--virtually all of them white, in contrast with the brightly colored species that live around ocean-bottom vents.
Such organisms were able to evolve in Lake Baikal as well as in oceans because of the existence of the vents and the lake’s age and isolation. The lake is, Crane said, “a living laboratory of evolution.”
At 25 million years old, Lake Baikal is a grizzled ancient compared to other lakes. Most lakes form and disappear over relatively brief periods of time, geologically speaking. The Great Lakes in the United States, for example, were formed only 18,000 years ago and the end of the last ice age.
Baikal, which is a mile deep at its center, contains one-fifth of the world’s fresh water and fully 80% of the fresh water in the Soviet Union.
But its isolated location, in southern Siberia about 200 miles north of Mongolia, had prevented much study of the underwater geology and biology. And although Soviet investigators had made underwater surveys revealing warm water that suggested the existence of the vents, the process of actually locating them was complicated by the absence of electronic navigating aids such as Loran that use radio waves to determine precise locations.
To overcome this problem, the expedition, organized by National Geographic photographer Emory Kristof, used hand-held navigational devices manufactured by Monrovia-based Magellan Systems Corp. to link up with the U.S. government’s $9-billion Global Positioning System of satellites--the first time the GPS system had been used in the Soviet Union, Kristof said. The devices used signals from the satellites to locate their position on board the research ship with an accuracy of 300 feet.
Tracking their position with GPS, the researchers first used an underwater, camera-equipped sled towed behind the ship to map a likely area of Baikal near Frolikha Bay at the lake’s extreme northeastern corner. On June 26, they made a significant finding.
“On the seventh run, after days of just looking at mud, we suddenly saw an area covered by sponges and long strands of bacteria,” Crane said. At the same time, sensors indicated that the water was at least 24 degrees Fahrenheit hotter than the chilly Siberian waters around it. The area of the vents was about the size of seven football fields.
They then used the three-person Soviet mini-sub Pisces to make 15 dives to the hot water vent about a quarter-mile down.
Columbia’s Crane noted that the water flowing from the vents is very unusual. Water in sub-ocean vents flows through volcanic rocks and thus contains a variety of minerals that would make it very foul-tasting. But the water at Baikal flows through marble (which is formed by the compression of sediments), and its composition should be “much like the San Pellegrino mineral water that you buy at your local bistro.” In effect, the hot water vent is an underwater spa.
Kristof was particularly impressed by one “very nifty” fish he observed near the vents, a species of black sculpin that was covered with lacy filigree. “If Frederick’s of Hollywood were going to build you a fish, that would be it,” he said.
In addition to diving to the hot water vents, the researchers also used remotely operated vehicles to explore much of the rest of the lake for the first time and collect biological samples. Baikal contains a large number of different species of sponges, and many new species were collected.
That collection is particularly important because the drug industry has long viewed the oceans as a primary source of new compounds with antibiotic and anti-tumor properties, and sponges have been the most prolific source of potentially useful compounds. The new sponges will be screened for their biological properties by chemist Shirley Pomponi of the Harbor Branch Oceanographic Institution in Ft. Pierce, Fla.
Within the next year, Soviet and American scientists also plan to study sediments at the bottom of Baikal to learn about the climatologic history in the area. Sediments in the ocean bottoms are routinely studied for such purposes: The nature of fossil organisms found in the sediments tells much about the climate at specific periods.
But there are no comparable studies on continents because most lakes are too transitory. The 25-million-year record at Baikal should give scientists their first direct indication of how climate changes affected land-dwelling species.
