Biological and ecological features of saline lakes in northern Tibet, China

In May and July 2001, the biological and ecological features of 22 salt lakes in northern Tibet, China, were investigated. Their salinity ranged from 1 to 390 g 1(-1). One hundred and thirty two samples were collected. Ninty five taxa of phytoplankton and 42 taxa of zooplankton were recorded. The dominant cation was sodium, with magnesium generally sub-dominant; CO32- was the dominant anion in low salinity, chloride 3 was the dominant anion with increasing salinity. Major species were Gloeothece linearis, Oscillatoria tenuis, Chroococcus minutus (blue-green algae); Navicula spp, Cymbella pusilla, Diatoma elongatum (diatoms); Dunaliella salina, Chlorella vulgaris and Ulothrix tenerrima (green algae). Major zooplankton included: Vorticella campanula, Epistylis daphniae (Protista); Keratella quadrata, Brachionus plicatilis (Rotifera); Artemia spp. (Anostraca); Daphniopsis tibetana (Cladocera); Cletocamptus dertersi and Cyclops vicinus (Copepoda). Ten species were recorded in hypersaline waters; apart from those mentioned above, they included Cyclidium spp., Litonotus fasciola, Euplotes terricola, Strombilidium viride, Brachionus variabilis, Colurella adriatica, Keratella cochlearis, Colurella adriatica, and Cyclops sp. Seven taxa of benthic macroinvertebrates are recorded, represented by Cypris sp. (Ostracoda), Gammarus sp. (Amphipoda), Radix sp. and Hippeutis sp. (Mollusca); chiroonomids Tendipus group salinarius (Diptera), Nematoda, Trochophora and Ephrdra sp. At present, there are fishes only in Bangong Co., and no fishes recorded in other salt lakes. The total number of plankton species has a significantly negative correlation with the salinity, and decreased with increasing altitude, but not significant.