A dynamic new alarm system for use in biological early warning systems

The Musselmonitor(R) (Delta Consult, Kapelle, The Netherlands) is a biomonitor that uses the valve position and the activity of eight Dreissena polymorpha to monitor the water quality. The normal behavior was studied to evaluate whether eight mussels are sufficient for reliable and reproducible data. The Musselmonitor was placed on a location with strong fluctuations of physical and chemical parameters. The results clearly indicate significant correlations between the valve position and the activity of the mussels and several parameters, such as temperature and concentration of suspended material (represented as turbidity and chlorophyll concentration). The valve position also indicates diurnal and seasonal rhythms in the natural behavior. A new data analyzing system was developed for the Musselmonitor, which takes into account the natural fluctuations in the behavior. The sensitivity of the dynamic data analyzing system was evaluated with copper (20, 40, 50, and 80 mu g/L) in dosage experiments and the results were compared with the existing static alarm system. The study revealed that static threshold levels are insensitive and require a lot of experience. The dynamic alarm system works satisfactorily with the Musselmonitor and is very useful for the detection of discontinuities in the normal behavior.