AQUATIC INSECTS IN FISHWAY BIOTOPE ON AONO DAM SITE

Abstract

Aquatic insects were surveyed to evaluate a biotope of Aono dam fishway ecologically. The Aono dam is located on the Aono river, a tributary of the Muko river which flows through Hyogo Prefecture, Japan. The fishway consists of pool-type fishway, riffle and pool sequences and etc. Aquatic insects were sampled by picking up surface bed materials in about 0.09m₂ quadrat and washing adhered materials out. Sampled aquatic insects were identified to genera and individual numbers were counted for each genus. The genera and their individual numbers were examined in relation to hydraulic and bed conditions. EPT, Shannon Diversity Index and etc. were calculated for each sample. Most sampled insects belongs to genera which have tolerance to organic pollutions and usually live in lower reaches. Algae and mud which are supposed to come from the dam reservoir strongly influence spatial distribution of the genera of insects.