Temporal dynamics of production and its trophic basis in two caddisflies (Hydropsyche sp. and Neureclipsis sp.) in Hujiaxi Stream, a second-order stream in Middle China

During the period of April 2006 to March 2007, we conducted an investigation on life cycle, annual production, and trophic basis of two dominant caddisfly species, Hydropsyche sp. and Neureclipsis sp., in a second order river (Hujiaxi Stream) of the Qingjiang River basin. The two caddisflies both appeared to develop two generations per year, and there was a little overlap in the two generations. The annual production and P/B (production/biomass) ratio were 8.54 g/m(2) and 11.44 for Hydropsyche sp. and 0.35 g/m(2) and 7.65 for Neureclipsis sp. Foregut content analysis revealed that amorphous detritus constituted the bulk of the diet. The annual average percentage composition was 92.3% for Hydropsyche sp. and 81.1% for Neureclipsis sp. Animal material, vascular plant detritus, and algae constituted the remainder.