Relationship between herbicide mode of action and difference in species sensitivity of aquatic primary producers

Abstract

Relationship between herbicide mode of action and difference in species sensitivity of 6 species primary producers（Pseudokirchneriella, Desmodesmus, Navicula, Anabaena, Synechococcus, and Lemna） was investigated. Toxicity data of 6 species for 120 herbicides was organized. The toxicity data was converted to standardize the difference in toxicity among herbicides as species sensitivity index（SSI）. The SSI indicates the relative difference in species sensitivity, and higher SSI means higher sensitivity. Pseudokirchneriella was not the significantly most sensitive species to herbicides of each mode of action. On the other hand, Lemna was the significantly most sensitive to herbicides of 2 mode of action groups（inhibitors of acetolactate synthase and 4-hydroxyphenyl-pyruvate-dioxygenase） . Desmodesmus was the significantly most sensitive to herbicides of a mode of action group（inhibitors of protoporphyrinogen oxidase）. These results suggest that difference in species sensitivity is specific to the mode of action, and a single species cannot always represent the sensitivity of primary producers to herbicides.