西藏地区现代沉积物中介形类环境指示意义初探

Preliminary study on environmental implications of ostracodes in modern deposits in Tibet

于2008和2012年先后2次从西藏阿里和那曲地区61个不同水体,包括不同盐度的湖泊、湿地、浅水坑和河流等,共采集了78个水体表层沉积物样品,用以研究该地区现生介形类的生态分布及其环境指示意义.经鉴定,阿里和那曲地区现生介形类共计11属38种.除Ilyocypris neoaspera等5个种外,本次调查的介形类各属种均在湖泊中出现,尤以Limnocythere dubiosa的总壳瓣数最为丰富.Ilyocypris属中除Ilyocypris subdunshanensis和Ilyocypris xizangensis外,其余各种均喜浅水坑的小型浅水环境.Leucocythere dilitata、Limnocythere dubiosa、Limnocytherellina kunlunensis和Eucypris rischtanica为该地区的广盐种.其中Limnocythere dubiosa和Leucocythere dilitata适应盐度范围最广,在不同盐度的各类水体中均有出现.本次研究中的介形类均喜碱性水体,在p H值为8~9的水体中介形类各属种的丰度值达到最大.

78 surface sediment samples in 61 different water bodies,such as lakes with different salinities,swamps,shallow puddles and rivers,in Ali and Naqu regions in Tibet,were collected to study the ecological distribution of extant ostracodes and their environmental implications. Total of 11 genus and 38 species living ostracodes are identified. All kinds of ostracodes in this research area are found in lakes except for the Ilyocypris neoaspera and other 4 species,and the number of Limnocythere dubiosa is the most abundant in the lakes. All Ilyocypris species prefers small and shallow water like shallow puddles except I. subdunshanensis and I. xizangensis. Leucocythere dilitata,Limnocythere dubiosa,Limnocytherellina kunlunensis and Eucypris rischtanica are euryhaline species in these regions,among which L. dubiosa and L. dilitata have the strongest tolerance for salinity and they have been found in a variety of water bodies with different salinities. Ostracodes prefer alkaline water and have the maximum abundance in water bodies with p H values of 8-9.