Auswirkungen der Wasserqualität auf die elektrischen Signale von Apteronotus albifrons (Linnaeus, 1766)

The experimental subjects of this study were the weakly electric fish of the genus Apteronotus albifrons. It was tested if these fish modulate their characteristic electric organ discharge (EOD) with respect to either frequency or wave-form in response to changes in the physical properties of their surrounding water. Changes, which affected the animals´ metabolism, were demonstrated to alter the discharge frequency. Reduction of metabolic activity resulted in a reduced discharge frequency and vice versa. In contrast, alteration of metabolic parameters showed no effect on wave-form. Alterations in EOD wave-form could however, be produced by altering either water conductivity or oxygen concentration. The intensity of wave-form modulation was found to increase with increasing water conductivity. This was maximal at 280µS/cm and was more intense when conductivity changes were generated using HNO3 than with NaCl. Reduction of oxygen concentration in the test aquarium was also found to change the wave-form. This could be reversed by restoration of the control oxygen concentration. Each individual fish was found to have its own characteristic wave-form. Furthermore, experimentally induced alterations in this wave-form were also characteristic for each individual but could not, however, be inferred from the original pattern. No experimental parameters were found which could simultaneously modulate both wave-form and frequency