Influence of photoperiod on visual prey detection in the Antarctic fish Notothenia neglecta

Abstract

Reaction to the presence of prey, after visual stimulation, was tested in the Antarctic nototheniid fish Notothenia neglecta Nybelin under four different simulated Antarctic seasons - photoperiods of 24 hours light, 22 light/2 darkness, 12 light/12 darkness, and 24 hours darkness. Live Lepidonotothen nudifrons were used for visual stimulation, with exclusion of chemical and mechanical signals. The photoperiod showed significant correlation with the number of individuals stimulated and with the latency time of the first response to the presence of prey, but not with the number of attacks or pursuits. However, there were more pursuits in darkness than in light. Notothenia neglecta presumably perceive a large spectrum of wavelengths, because they had the shortest reaction time under red light, used to simulate darkness. The tests proved that N. neglecta are capable of detecting prey using only vision, in all seasons of the year, but that the optimal reactions occur in a photoperiod corresponding to the Antarctic autumn or spring.