Seasonal variation of mayflies (Insecta: Ephemeroptera) in tropical andean headwater stream

Abstract

The mayfly fauna of an Andean tropical headwater stream was sampled every fifteen days during one year, and seasonal changes in density were recordered and compared to rainfall values. Even though seasonal changes of total density of genera of Ephemeroptera showed a negative correlation with rainfall values, any correlation was observed for individual genera. Two patterns were nevertheless evident: Nymphs of Baetodes, Leptohyphes, Thraulodes, Andesiops and Prebaetodes were abundant all year round, whilst nymphs of Haplohyphes, Trichorythodes, Farrodes and Americabaetis were only present occasionally and occurred in low densities.