Life History, Secondary Production, and Trophic Basis of Four Dominant Mayflies in a Second Order Stream, Tanqigou Stream, China

ABSTRACT Mayflies were investigated in a second-order montane stream of the Qingjiang River basin, among which Electrogena sp., Indobaetis sp., Choroterpes sp., and Caenis sp. were the dominant species, contributing 92.4% to the total mayfly standing stock. Electrogena sp., Choroterpes sp., and Caenis sp. all developed two generations per year, and there was little overlap with the two generations in each species. Indobaetis sp. had three generations a year. The average annual production of Electrogena sp., estimated by the size-frequency method, was 15.8 g (dry weight)/m2. Indobaetis sp. was 8.8 g/m2, Choroterpes sp. was 1.6 g/m2, and Caenis sp. was 0.9 g/m2. By foregut content analysis, we found that amorphous detritus was the most important food type, accounting for 77.8%-84. 4% of their diets and 62.0%-74.7% of their annual ingestion.