Production Dynamics and Trophic Basis of Dominant Chironomids (Diptera: Chironomidae) in a Subtropical Stream in China

Abstract

ABSTRACT During the period of June 2003 to June 2004, we investigated production dynamics and trophic basis of seven dominant species of chironomids in a second-order river of the Hanjiang River basin in China. Tvetenia discoloripes was by far the most abundant chironomid, and it was the most productive species, with an estimated annual production of 24.06g • m−2. Pentaneura sp. and Eukieferiella potthasti had production values >3.50 g•m−2, and all other species had values <2.00g • m−2. Temporal distribution patterns of production tended to follow biomass patterns. Tvetenia discoloripes, Chaetocladius sp., and Pagastia sp. concentrated most production in winter, while E. potthasti, Pentaneura sp. and Polypedilum sp. had relatively high production throughout the year. Overlap in temporal distribution of production among the chironomid species was generally high (>0.5), especially for the filter-collectors Microtendipes sp., Chaetocladius sp., T. discoloripes, and Pagastia sp. All species except Pentaneura sp. consumed a large portion of amorphous detritus, constituting more than 90% of their diets and contributing nearly 90% to their secondary production.