CCA Inferred Environmental Implications of Common Ostracods on the Qinghai-Tibetan Plateau

103 surface sediment samples in 71 water bodies,such as lakes with different salinity,swamps,shallow puddles and rivers on the Qinghai-Tibetan Plateau(QTP),were collected to study the ecological distribution of living ostracods and their environmental implications. Total of 12 genus and 45 species living ostracods are identified. According to the frequencies and abundance of ostracods occurrence,Limnocythere dubiosa,Limnocytherellina kunlunensis,Ilyocypris bradyi,Candona candida,Eucypris rischtanica and Leucocythere dilatata are the common species on the QTP,with occurrence frequency of more than 8 and abundance of more than 570 in the 71 water bodies. Among them,L. dubiosa,occurring in 28 water bodies with 2177 shells,is the most widely distributed ostracod in this research. Canonical Correspondence Analysis(CCA) indicates high correlation between species and environmental variables,suggesting that the occurrence of species is strongly related to the changes in ecological conditions of habitats. Among eight environmental factors,salinity and p H value are the most affective variables that influence the species occurrence. L. kunlunensis is positively correlated with salinity while E. rischtanica is negatively correlated with salinity. C. candida has a positive correlation with salinity,as does I. bradyi although there is not such a strong correlation. L. dubiosa displays a positive correlation with p H value. Consequently,we discuss the environmental implications of the common living ostracods on the QTP based on the CCA as well as the distribution of ostracod species in different salinity and p H values water. L. dubiosa,L. kunlunensis and E. rischtanica are euryhaline species,among which,L. dubiosa is the most adaptable species on the QTP with large occurrence in sundry salinity water and the most widely adaptive range for p H values. L. kunlunensis prefers to saline water while E. rischtanica prefers to fresh water. Both L. kunlunensis and E. rischtanica can live in water from faintly acid to alkaline,in contrast,L. dubiosa only appears in neutral and alkaline water bodies. I. bradyi only occurs in fresh water and oligohaline water with a large p H tolerance range tolerance range from weakly acidic water to alkaline water weakly acidic water to alkaline water. C. Candida lives in freshwater,with p H value above eight. The six common species reach maximum abundance in alkaline water(p H 8-10) except for Ilyocypris bradyi.