Abstract

Static biotests as Daphnia test and algae test are well introduced in the check of water quality. But although they are often called "acute" tests they are not able to signal short term accidents or time-depending variations of toxic substances. Biomonitoring systems were set up to serve as "early warning systems". Biomonitors are 24 hours a day working systems using organisms to indicate changes due to the release of toxic substances.
This paper deals with the measurement of changes in the behaviour of Daphnia with the bbe Daphnia toximeter. Speed, speed distribution, height, distance between organisms, number of Daphnia and "fractal dimension" are evaluated to account for the appearance of toxic substances. By that way even low concentrations not leading to the death of Daphnia can be detected within minutes.
Results of the last two years of field experience and laboratory tests are performed.