DaphTox II source-water protection

Sensitive detection of toxic substances in water via computer-assisted digital image analysis

The bbe DaphniaToximeter II observes daphnids, commonly known as “water fleas”, under the influence of constantly running sample water. Based on the Extended Dynamic Daphnia Test, bbe developed a new sensitive method to detect hazardous compounds in water from rivers (source-water protection), plants, distribution systems and production drains to preserve human health and to monitor water.

Sensitivity data are available below.

Sample water (0.5 – 2 l/h) continuously runs through the measuring chamber containing the daphnia. The live images obtained using a CCD-camera are evaluated online with an integrated PC to analyse changes in the behaviour of the daphnia. If the change is statistically significant, an alarm is triggered. The method of image analysis enables a series of measurement methods and plausibility tests to assess the daphnia’s behaviour using different criteria.

Measurement using digital image analysis
Observation of speed parameters:

• average speed
• speed distribution
• distance between daphnia

Observation of behaviour:

• swimming height
• location
• fractal dimension: measurements for turns and circling movements, curviness

Observation of growth:

• determination of daphnia size

Toxicity Index
The concept of the toxicity index is based on the evaluation of certain measurands, such as speed or height, and changes in these measurands. Only when 2 or more of the measurands simultaneously show unusual results within a fixed period of time does the DaphTox II trigger an alarm.