Present Biodiversity of the Former Aral Sea and its Importance for Remnant Water Bodies Rehabilitation
Dr. Nick Aladin, Head, Laboratory of Brackish Hydrobiology, Russian Academy of Sciences, St. Petersburg, Russia
The Aral Sea was the 4th largest lake in the world by water surface area and slightly saline with average salinity about 10 g/l in 1960. It was inhabited by about 12 fish species and 150 species of free-living macro-invertebrates. Until 1961 the shape and salinity practically didn't change since the middle of the 19th century. Due to intended and accidental introductions, the number of free-living animals grew since the 1920s. 21 new fishes and 16 new macro-invertebrates appeared. Since 1960 the Aral Sea became shallower and salinity grew owing to increased water consumption for irrigation. At the end of 1980’s, the Aral Sea divided into the Large and Small Aral with salinity about 30 g/l and only 10 fishes and 15 macro-invertebrate species could survive. Salinity in the Large Aral continued to rise and reached 100 g/l (western part) and 160 g/l (eastern part) in 2007 and all fishes disappeared and only a few invertebrates survived, while in the Small Aral it decreased and reached 12 g/l in 2007. There are 4 main ways of conservation and rehabilitation of Aral Sea and its ecosystems that were first discussed September 1992 at UNEP meeting in Geneva.