Aquatic insects in the lower reaches of the Hirose River

In order to elucidate the species composition of aquatic insects in the lower reaches of the Hirose River, Miyagi Prefecture, aquatic insects were monitored once a month from April 2001 to January 2002 at two stations (St.1: Hirosebashi, and St.2: Sendai-ohashi). The two sites were approximately 1.5 km apart, and St.1 was located upstream. A total of 2,862 aquatic insects from 43 taxa belonging 25 families were collected at the two stations. Among the 43 taxa collected, Drunella basalis (Ephemeroptera), Hydropsyche orientalis (Trichoptera) and Cincticostella (Cineticostella) elongatula (Ephemeroptera) were dominant in number, and D.basalis, Stenopsyche marmorata (Trichoptera) and C. (C.) elongatula were dominant in the standing crop. Although the taxon richness and total standing crop did not differ significantly between the two sites, total number of individuals was significantly lower in St.2 (p<0.01) as determinrd by unreplicated two-way ANOVA.