Abstract
Two species of chironomids Cricotopus tamapullus and Paratrichocladius rufiventris predominantly emerged from six outdoor artificial channels, first four, and then three of which were exposed to ABS. Chironomid emergence was decreased by exposure at about 2.7 ppm average concentrations for one month, but showed no decrease at concentrations of about 1 ppm or lower for three months. The results suggested that the decrease in chironomid emergence was attributable to negative effects of ABS at the time of emergence or at aquatic life stages. The latter possibility was suggested as a secondary effect by the fact that attached algae were decreased by exposure at 2.7 ppm.
