THE SWIMMING BEHAVIOR OF BRACHIONUS-CALYCIFLORUS (ROTIFER) UNDER TOXIC STRESS .1. THE USE OF AUTOMATED TRAJECTOMETRY FOR DETERMINING SUBLETHAL EFFECTS OF CHEMICALS

Changes in the locomotory behaviour of the freshwater rotifer Brachionus calyciflorus were were used as sublethal indicators of toxic stress. To that end, the swimming behaviour of this rotifer was analysed using an automated tracking system. The swimming speed (temporal factor), the swimming sinuosity (spatial factor), and the periods of swimming were measured and the influence of four chemicals, each representing a distinct chemical class (copper, pentachlorophenol, lindane and 3,4-dichloroaniline), on the rotifer's swimming characteristics were examined. The three test parameters exhibit different sensitivities depending on the chemical tested. The 2-h EC(50)s obtained with the behavioural test were of the same order of magnitude as the 24-h LC(50)s resulting from conventional acute toxicity tests with the same test species. This potential use of behavioural test criteria for sublethal toxicity testing with rotifers is briefly discussed.