Russian Giant Feeling The Heat

Posted on Mon May 12 2008

By: Hilary Feldman in Environment

Comments: 1

Share: Digg | Hugg | Del.icio.us | Reddit | Email

Lake Baikal is the largest lake in the world. Located on the Irkutsk border, it is also the deepest at more than 1,600 metres in places. Now, a team of researchers has looked at various lake characteristics and published their findings in Global Change Biology. Long-term studies over the past 60 years show that the lake is now 1.21 degrees Celsius warmer than in 1946. While it may not sound like much, the change is significant over such a short time period.

Designated a World Heritage Site in 1996, the lake holds one-fifth of the world’s freshwater. Lake Baikal is an ancient lake set in a bowl of mountains with a single drainage - Angara River. It is home to about 2500 plant and animal species, including 852 species of algae. Many of these are endemic, including the Lake Baikal seal, or nerpa, the only freshwater pinniped. The lake has a high oxygen content, even at depth, so that animals thrive in all areas. In contrast, many deep lakes have anoxic zones and lack life at greater depths. Additionally, Baikal has several areas with hydrothermal vents, providing habitat for other unique organisms.

Since the 1950s, there has been increasing pollution in the lake, due to industrial, agricultural, and residential development around the shoreline. Although there is increased regulation of many pollution sources, municipal and pulp mill effluents are still present, especially in South Baikal. However, the lake’s water is considered drinkable without any treatment, according to some sources.

The reported results are based on a remarkable data set, collected by three generations of one family and covering every season. Some of the findings are particularly significant. Along with general warming of the water, chlorophyll a measurements have increased (300% greater than in 1979), as has the cladoceran population (335% greater than in 1946). Both nutrient cycles and food webs may be shifting, as both algae and zooplankton dynamics shift with water temperatures.

In a typical winter, Lake Baikal freezes over from January to May. In the summer, surface waters warm to 20 degrees Celsius near shore, with much colder water layers below. In fact, the vast volume of water makes the lake a major regulator of the local area - cooling the land in summer and warming it in early winter.

Other important large lakes are also showing similar signs of warming, including Lake Superior and Lake Tahoe in North America, as well as Lake Tanganyika in Africa. Lake Baikal was thought to be less influenced by climate change, due to its northern location and huge size. Now that warming and other changes have been detected in Lake Baikal, there is an increased need to monitor other major freshwater ecosystems.

Comments