Sub-Recent Ostracoda from Bosten Lake, NW China

Abstract. In spite of early work by Daday (1903) and by Sars (1903a, b), the Recent and sub-Recent non-marine ostracod faunas of NW China remain poorly known. There is only little information included in later works, which have tended to focus on fossil Tertiary and Quaternary ostracods (e.g. Sun et al., 1999), rather than on Recent or sub-Recent taxa, although Yu & Martens (1997) have presented a very preliminary checklist for China as a whole.

In an attempt to improve this situation, this note reports on ostracods collected from the largest ‘freshwater’ lake of NW China. Bosten Hu (Lake) (c. lat. 42°N, long. 87°E) covers an area of about 1020 km² at an altitude of 1048 m above sea-level in an intermontane basin of the Chinese Tianshan Mountains. The lake has an outlet to the Tarim Basin in the south and had a salinity of about 1.0 g l⁻¹ in 1950 which increased to 1.5 g l⁻¹ in 1978 due to withdrawal of water from the main tributary (Kaidu He) for irrigation purposes. The lake is rather shallow with a maximum depth of 15.7 m, its volume being about 9.9 km³ (Berkner, 1993).

Sampling of surface mud from the uppermost centimetres of the lake bottom and of plankton samples was carried out along several transects in nearly all parts of the lake. Altogether, 33 samples were collected by a mud grabber or a handnet, and by a diver. Surprisingly, no living specimens were found, although ostracod valves were very abundant in . . .