2011 Volume 14 Issue 1 Pages 57-68
The effects of Cu on the riverine ecosystems in Japan were investigated mainly based on number of macroinvertebrate taxa and Cu and/or Zn concentrations in the metal-polluted rivers. The effects of Cu to macroinvertebrate communities were analyzed on the samples （n=159）after excluding the samples collected from stations where Zn concentrations were higher than 30 μg/L, estimated acceptable to macrobenthic fauna based on the first step assessment of Zn, to eliminate its joint effects to Cu. A regression equation between Cu-concentrations and number of taxa of macrobenthos（almost aquatic insects）, Y（number of taxa）= 38.0 - 31.4 ×（log10（Cu）- 0.627, R2= 0.5）, suggested that an acceptable copper concentration for macroinvertebrate communities is 4.2 μg/L （95 % confidence interval, 2.5 - 7.1 μg/L）. However, possibility of over- or under estimates of copper effects still exists, because the river waters were polluted with several metals such as a Cd, Pb, and Fe. Their contribution to decrease in number of taxa was assessed by multiple regression analysis and/or other factors（in the text）. On the order level, Ephemeroptera and Plecoptera are more susceptible to Cu pollution than Trichoptera and Diptera.
