The aquatic biota from the late Late Pleistocene was sampled below 46m in the well Dacan 1 of Qaidam Basin.They showed a high abundance and high diversity. The ostracoda was Cyprideis torosa-Ilyocypris inermis assemblage and associated with Carophyta, Gastropoda, Pelecypoda, plants and fishes. The aquatic biota from 46 ~10 m of depth in the well Dacan 1 was the sediments from the Great Ice Age of the Last Glacial Stage. In that time, the climate was rather arid and iciness, so that the geological event of playa occurred. The deposits rapidly developed from lake facies mudstone to halite. It was hard to find fossils,and most of biota disappeared completely. The Three-Lake Depression (Taijinaier Lake、Dabusun Lake and Huobusun Lake ) was entirely covered by about 40 m of salt bed, which became the last barrier for preserving natural gas, namely the cover of the gas reservoir. The deposits above 10m in the well Dacan 1 gradually developed into shallow lake mud- stone and silt gypsiferous salt,which wrere formed in the Holocene warm stage (modern interglacial stage) , or the first stage of oxygen stable isotope. In this stage the salinity of the region decreased and the biota abundance and the biota diversity increased again. The ostracoda was replaced by an assemblage of Candona neglecta-Candoniella lactea, which was adapted to the environment of  the slight brackish and fresh water. It also associated richly with Carophyta, Gastropoda, Pelecypoda,etc.
Up to now, there has been abundant aquatic biota in the south of Taijinaier Lake、Dabusun Lake and Huobusun Lake because of the supply of freshwater from Kunlun Mountains. However, the water is relatively salty in the north of Taijinaier Lake、Dabusun Lake and Huobusun Lake due to the great distance away from the main supply of freshwater. The ostracoda was replaced by the typical salty-lake ostracoda Eucypris inflata assemblage. The distribution of gypsum-saline beds in the north is obviously more than that in the south of Taijinaier Lake,Dabusun Lake and Huobusun Lake.