武汉东湖的透明薄皮溞

本文报道了东湖大型肉食性枝角类——透明薄皮溞（Leptodora kindti）种群的周年变动昼夜垂直迁移及体长-体重回归方程。在I站1984年的高峰出现在8月, 1985年出现在7月, 数量分别为1.775和0.313 ind./L;且站均出现在9月, 数量分别为1.214和1.547 ind./L。透明薄皮溞有明显的昼夜垂直移动现象, 衣层的数量变动更明显, 通常以日出及日落前后1小时, 衣层数量最多, 用直接测重法测定了不同体长组的湿重、干重, 经统计处理获得了各自的回归方程。

Leptodora Kin Dti Focke (1844) (Cladocera: Leptodoridae) In Donghu Lake, Wuhan

The results of population dynamic, diurnal vertical migration and regression equation for the body weight and weight length of Leptodora kindti are reported. The maximum population density for Leptodora kindti was 1.775 ind./L in 1984, and 0.332 ind./L in 1985 at Station I, 1.214 ind./L and 1.547 ind./L at Station II, rcspcctivcly. Changes in the relative numbers of animals at three specific depths (surfacc, 1.00 and 2.00 meter) occur with time. Surfacc changcs arc of much greater magnitude, although highly significant diffcrcncc exists at all three sampling depths. Preliminary investigation shows that the general pattern of diurnal migration is to be one in which more individuals were found at surfacc within one hour before and after sunrise and sunset, while less numbers were observed at surfacc during daytime. By weighted, the wet and dry weights were determined, and their relationships to the body length arc expressed by various regression equations.