IMPORTANCE OF CORYDALIDAE AS AN INDEX OF METAL CONTAMINATION OF RIVER

Abstract

Larva of Corydalidae, a kind of dobsonfly was useful for evaluating a metal contamination of
catchment. Dobsonfly larva eats many kinds of aquatic insects as food. Then, metal derived from wide area
of river soil and river water is concentrated in the dobsonfly larva for long term by food chain. The average
Cu, Fe, Mn, Pb, Zn and As concentrations of dobsonfly larva under the polluted zone was high. Metal
concentration of dobsonfly was clarified to be strongly influenced by river metal condition as well as mayfly
and caddisfly. Cu, Fe, Mn, Pb, Zn and As concentration factors for dobsonfly were very variable depending
on river metal concentration and totally the average factors for dobsonfly were almost similar values for
mayfly and caddisfly. However, caddisfly and mayfly are clarified into many kinds of species and
concentration factor depends on each specie. Dobsonfly is 2 or 3 species in Japan. Therefore, dobsonfly was
thought to be useful for Cu, Fe, Mn, Pb, Zn and As contamination indicator.