Author(s): Guo Xianwu
Pages: 578-585
Year: 1995 Issue:  6
Journal: Journal of Huazhong Agricultural University
Keyword:  chironomid larvae; community; vertical distribution; movement;
Abstract: Quantitative samples including vertical-stratification samples of chironomid lar-vae were collected in Nanhu Lake, Wuhan, China, in 1987 ~ 1988 and in May, 1991. Fifteenspecies belonging to ten genera and three subfamilies were found. Tanypus chinensis Wang, Prop-silocerus akamusi (Tokunaga) and Chironomus plumosus f. semireductus Lenz were three dominant forms. The larvae showed different vertical distribution in the muddy bottom. Most species were present at depths of 0~20 cm, while P. akamusi moved to the deeper ooze with 90% of larvae at 20~40 cm from May to October. The average density of chironomids was 1392 ind/m2 with a min-imum of 315 ind/m2 in May, and a maximum of 2941 ind/m2 in September. The average biomass was 10. 4 g/m2 with a maximum of 22. 9 g/m2 in December. The limiting factors for horizontal dis-tribution vaires among different species. The vertical distribution of P. akamusi might be due to the presence of temperature above 19℃. Species with vertical movements can be classified into two groups, summer-downmove and winter-downmove. Both of them influence apparently the sampling results if a Peterson or an Ekman-Birge grab is used.