Changes in Abundance of Benthic Macroinvertebrates in a Pesticide-contaminated River.

概要

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Changes in benthic macroinvertebrates and concentrations of pesticide residues were surveyed at two stations in the Kajinashi River from April 1989 to September 1990, focusing especially on the periods before and after transplantation of rice plants into paddy fields bordering the river. Fenobucarb (BPMC), butachlor and oxadiazon reached their peak concentrations (4.6-12.5 μg⋅1-1 at upper site, 3.9-22.4 μg⋅1-1 at lower site) soon or one month after rice transplantation. The other pesticides (e. g. fenitrothion, fenthion, chlornitrofen) were detected at peak concentrations below 1, μg 1-1 at each site. The density of Cheumatopsyche brevilineata (Trichoptera) larvae increased markedly, but larvae of Antocha sp. (Diptera) decreased after fenobucarb had reached its maximum concentration at the lower site. The 48-h LC50 values of insecticides and herbicides for the final instar larvae of both species were higher than those of concentrations detected in the river. However, Antocha sp. was more sensitive than C. brevilineata to fenthion (48-h LC50 values, 120 and 820 μg⋅1-1, respectively).
日本陸水学会の論文