中文摘要：

大型底栖动物在河流生态系统中发挥着重要作用。2003年6月至2004年6月间对汉江流域2级河流——黑竹冲河大型底栖动物群落优势种类的生产力进行了为期一周年的调查研究。结果表明，主要优势种小裳蜉（Leptophlebia sp．）和蜉蝣（Ephemera sp．）的生活史均为一年两代，蜉蝣的两个代之间界限比较明显；小裳蜉成虫羽化主要发生在秋季和冬季，而蜉蝣成虫羽化主要发生在夏季和冬季。小裳蜉和蜉蝣种群的生物量和多度均出现两次峰值。采用体长频率法（size-frequency method）测算的周年生产量分别为：小裳蜉，38．0362g·m^-2·a^-1，P／B为11．4：蜉蝣，76．0318g·m^-2·a^-1，P／B为11．8。

英文摘要：

Macrozoobenthos community plays an important role in material cycle and energy flow in riverine ecosystem. During June, 2003 to June 2004, an investigation on the life cycle and production of dominant species of macrozoobenthos community in a second-grade river of Hanjiang River catchment was carried out. From the upper reach to the lower reach of Heizhuchong stream, we chose six types of habitats to sample. Station 1 （S1） lied in the middle of the stream with big round rocks there in the upper reach, station 2 （S2） was in the inner part of a weir with cobble substratum, station 3 （S3） in the middle of a peacefully flowing section with gravel-sand bottom, station 4 （S4） at the side of the riparian with aquatic macrophytes and snags, station 5 （S5） was in the middle of the rime, station 6 （S6） at the lower reach with a sewage outlet ca 100 meters upper. At each station, two quantitative samples were taken with a 167μm Surber net, and the samples were sieved with a 167μm net, sorted in a porcelain dish with naked eye. The specimens were kept in 10% formalin for later processing. The life cycle ofLeptophlebia sp. and Ephemera sp. was analyzed by the monthly size frequency distribution, the cohort and annual production were estimated by size frequency method. The results showed that the dominant species Leptophlebia sp. and Ephemera sp. appeared to develop two generations per year, and there was a little overlap with the two generations ofLeptophlebia sp., but it could not be a matter to make out the two generations. As far as Leptophlebia sp. was concerned, the pupation mainly occurred in fall and winter; while pupation of Ephemera sp. mainly occurred in summer and winter; the abundance and biomass of the Leptophlebia sp. population reached their highest peaks （913 ind. · m^-2, 0.992 0 g·m^-2） in October and August, respectively, while the abundance and biomass of the Ephemera sp. population reached theirs （107 ind · m^-2, 2.363 9 g·m^-2） in June and March. The cohort production