Circadian self-feeding rhythms in greater amberjack Seriola dumerili (Risso) |
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Authors: | W-M Chen † N Umeda † T Mitsuboshi † N Hirazawa † |
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Institution: | Oita Marine Biological Technology Center, Central Research Laboratories, Nippon Suisan Kaisha, Ltd, 508-8 Ariakeura, Oaza, Tsurumi, Saiki, Oita 876-1204, Japan |
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Abstract: | In the present study, 10 greater amberjack Seriola dumerili held individually were given free access to self-feeder, and trigger actuations were continuously monitored. Most (80%) of greater amberjack developed stable self-feeding activity within 1 week. The fish was a rigidly diurnal feeder under a 12L:12D cycle, with a feeding peak of 1–3 h occurring just after the onset of lights. Under constant conditions, all 10 individual fish exhibited free-running self-feeding rhythms, which persisted for 43 days without a sign of damping out. As far as is known, this seems to be the longest record of free-running behavioural rhythms in fishes. Except one fish free-ran at a period length (τ) of 25·2 h, τ of free-running self-feeding rhythms in the other nine fish was shorter than 24 h, ranging from 20·0 h to 21·5 h. In addition, phase transients of feeding activity were observed in response to the advancement of lights on. It is concluded that feeding activity in greater amberjack is mediated by endogenous circadian oscillators. |
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Keywords: | circadian rhythms greater amberjack light-dark cycle self-feeding Seriola dumerili |
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