Evaluation of the responses to the photoelectrochemical stimuli on the swimming behavior of Aurelia aurita and its application for their ecological control

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Understandings of the biology and especially of the swimming behavior of the jellyfish, Aureria aurita, will bring us keys to solve the problems with jellyfish stopping the water intake pipes at power plants and ships, and also to reduce the troubles in fisheries. In order to do this, it was studied whether the swimming of jellyfish is controlled with moderate or even weaker stimuli such as light, sound and electricity either in continuous or in modulated manners.1) In the laboratory water tank the swimming behavior of jellyfish were traced by using the scatterings of laser light or ultrasound and also by the graphical image positioning. From the tracing after the locomotion of jellies upon stimulation by the electricity supplied with a potentiostat or light illumination with LED, laser and fluorescent light, any specific influence was not seen on their averaged swimming behaviors with the stimulation levels employed.2) With the video image analysis, the cross section of the pulsating and swimming jellyfish were evaluated in time series for up to several 10 minutes. The changes in the shape and the area of the cross-sectional image as a function of time showed that this monitoring method is quite useful to analyze the transient response of medusae in the attitude and pulsating rate upon a variety of stimuli.3) The averaged pulsation rate for a given period of time showed negative change upon the light illumination possibly due to the adaptability to the stimulus applied. With the video image analysis the transient change in the pulsation rate of jellyfish was examined. Although there are individuality among samples the rate change after ON or OFF of illumination was shown to recover in several ten seconds which explains the negative change in the averaged pulsation rate based on the prolonged counting of them.