Method for detecting the presence of a contaminant in a liquid

A process for detecting the presence of a contaminant in a liquid, preferably water, comprising the following steps:

• a) a batch of small benthic aquatic macroinvertebrates is conditioned to enter a lethargic state
• b) said benthic aquatic macroinvertebrates are immersed in the liquid, each organism being isolated individually,
• c) the behaviour of each aquatic organism is continuously recorded during exposure;
• d) the behavioural data is analysed by means of a processing device to determine the behaviour of benthic aquatic macroinvertebrates
• e) the presence of toxic contaminants is determined on the basis of the behaviour of benthic aquatic macroinvertebrates;
• characterized in that the analysis of the data comprises the determination, for each of the species of said benthic aquatic macroinvertebrates, of an average behaviour representative of the movements of the benthic aquatic macroinvertebrates of this species over a given period of time, the benthic aquatic macroinvertebrates being placed during the observation period under conditions in which the absence of toxicity results in the maintenance of the entire batch of benthic aquatic macroinvertebrates in a lethargic state, said conditions being favourable to the maintenance of life of said benthic aquatic macroinvertebrates and comprising an absence of food supply during the observation period,
• and in that the determination of the presence of toxicity comprises comparing said average behaviour to the average behaviour of the lethargic state, the presence of toxicity being established when the average behaviour increases by at least a factor of two over a period of at least 10 minutes.