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(162) Aquatic behavioural biomonitoring with Crangonyx pseudogracilis (Crustacea: Amphipoda); manual and automated techniques. Kirkpatrick, Anita1, Gerhardt, Almut2, Dick, Jaimie1, Berges, John1, 1 2 ABSTRACT- Behavioural changes may occur at sub-lethal toxicant levels and, as such, can be used as biological early-warning systems. Invertebrates are useful test organisms because they require modest holding facilities, they are exempt from animal-care regulations that govern vertebrates, and they are easy to obtain. Crangonyx pseudogracilis (Crustacea: Amphipoda) is a freshwater species exhibiting a range of definable behaviours (e.g. inactivity, swimming, grooming, escape) which are sensitive to environmental change. Behaviour was examined in amphipods exposed to concentrations of ammonium chloride in the range 0.05 to 54 mg.l-1. The time spent in each behaviour for each individual was directly observed and recorded using the Observer™ system. This revealed progressive changes in behaviour, with an increase in the escape behaviour and decrease in grooming as ammonium concentration increased. Behavioural changes were detected at one-tenth of 96 h LC50. To overcome the time consuming nature of behavioural measurements, the Multispecies Freshwater Biomonitor (MFB)™ was tested to determine if behavioural changes could be recorded objectively and automatically online for this species. Individuals were placed in chambers containing electrodes; behavioural changes altered the impedance, which was recorded for 4 minutes with 6-minute intervals. Full methodological details are presented in a poster by Gerhardt. Initially, the signals produced were identified as specific behaviours through simultaneous recording using the MFB and the Observer system. Ventilation (inactivity) corresponded to impedance signals at a frequency of 2.5-4.5 Hz, active behaviours corresponded to lower frequencies. Behaviour was recorded over a 48 hour period to establish normal behaviour and diurnal activity patterns. Further experiments with the MFB have recorded behavioural responses for 48 hours following the addition of ammonium chloride. Key words: behaviour, Crangonyx pseudogracilis, impedance converter, toxicity |
