Monitoring of surface water by ultrasensitive Daphnia toximeter

Static biotests, such as Daphnia and algae tests, are well known in the che cking of water quality. Although they are often called "acute" tests they a re not able to identify short-term accidents or time-dependent variations o f toxic substances. Biomonitoring systems were set up to serve as "early wa rning systems." Biomonitors are 24 h a day working systems, using organisms to indicate changes due to the release of toxic substances. This paper dea ls with the measurement of changes in the behavior of Daphnia with the bbe Daphnia toximeter. Speed, speed distribution, height, distance between orga nisms, number of Daphnia, and "fractal dimension" are evaluated to account for the appearance of toxic substances. In this way even low concentrations which do not lead to the death of Daphnia can be detected within minutes. Results of the last two years of field experience and laboratory tests are given. (C) 2000 by John Wiley & Sons, Inc.