Abstract: A one-year investigation from April 2006 to March 2007 was conducted on the production dynamics, trophic basis, and yearly ingestion currency of dominant chironomid species in a second order tributary (Hujiaxi stream) of Qingjiang River, a tributary of Yangtze River. Six types of habitat from the upper to the lower reaches of Hujiaxi stream were selected for sample collection, with the life cycles of the two dominant chironomid species Conchapelopia sp. and Eukiefferiella potthasti analyzed based on monthly instar-frequency distribution, the cohort and annual production estimated by size frequency method, and the production dynamics, trophic basis, and yearly ingestion currency examined by  the methods of Benke and Wallace (1997) and Benke (1980). Conchapelopia sp. had two generations a year, while E.potthasti had one generation a year. The mean annual density and mean annual biomass of Conchapelopia sp. were 105 ind·m^-2 and 0.1 g·m^-2, and those of E.potthasti were 280 ind·m^-2 and 0.3 g·m^-2, respectively. The annual production (wet weight) and the annual production/biomass ratio of Conchapelopia sp. were 1.2 g·m^-2 and 2.3, and those of E.potthasti were 1.4 g·m^-2 and 2.5, respectively. The temporal overlap of the production of the two species measured with proportional similarity index was 0.7, and the overlap mainly occurred in winter and spring. Amorphous detritus was the main food of Conchapelopia sp. and E. potthasti, occupying more than 84% of their diets and contributing 80.1% and 68.6% to their production, respectively. The yearly ingestion currency of Conchapelopia sp. and E. potthasti was 7.2 and 7.1 g·m^-2, respectively.

Key words: Crustacean, Starvation, Ecophysiology