天然付着珪藻群集に対する除草剤の影響と生物指標の適用可能性

抄録

The effect of herbicides on attached diatom communities was investigated to understand the differences in species sensitivity and the applicability of diatom-based metrics. Diatom community collected from the natural environment was exposed to seven herbicides with various modes of action for three days in a controlled laboratory condition. Five genera of diatom dominating in the control experiment were subjected to the data analysis. The order of sensitivity to herbicides did not differ markedly among herbicides: Fragilaria ≒ Achnanthidium > Navicula ≒ Planothidium > Nitzschia. The result that the difference in species sensitivity was not specific to the mode of action suggests the possibility of a simple classification into herbicide sensitive/tolerant species. Then, several biological metrics for species composition were calculated such as genus number and Shannon's diversity. SPEAR_herbicides as an indicator of the herbicide effect on the diatom community was less detectable. Instead, a modified SPEAR index based on the present study would be a better indicator of the herbicide effect on the diatom community.