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Appears in Collections:Aquaculture Journal Articles
Peer Review Status: Refereed
Title: Circadian Rhythms of Locomotor Activity in the Nile Tilapia Oreochromis niloticus
Author(s): Vera, LM
Cairns, Louise
Sanchez-Vazquez, F Javier
Migaud, Herve
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Keywords: Circadian rhythms
Locomotor activity
Nile tilapia
Nile tilapia
Circadian rhythms
Issue Date: May-2009
Date Deposited: 17-Jun-2009
Citation: Vera L, Cairns L, Sanchez-Vazquez FJ & Migaud H (2009) Circadian Rhythms of Locomotor Activity in the Nile Tilapia Oreochromis niloticus. Chronobiology International, 26 (4), pp. 666-681.
Abstract: Behavioral rhythms of the Nile tilapia were investigated to better characterize its circadian system. To do so, the locomotor activity patterns of both male and female tilapia reared under a 12:12 h light-dark (LD) cycle were studied, as well as in males the existence of endogenous rhythmicity under free-running conditions (DD and 45 min LD pulses). When exposed to an LD cycle, the daily pattern of activity differed between individuals: some fish were diurnal, some nocturnal, and a few displayed an arrhythmic pattern. This variability would be typical of the plastic circadian system of fish. Moreover, reproductive events clearly affected the behavioral rhythms of female tilapia, a mouth-brooder teleost species. Under DD, 50% (6 of 12) of male fish showed circadian rhythms with an average period (t) of 24.1+0.2 h, whereas under the 45 min LD pulses, 58% (7 of 12) of the fish exhibited free-running activity rhythms with an average t of 23.9+0.5 h. However, interestingly in this case, activity was always confined to the dark phase. Furthermore, when the LD cycle was reversed, a third of the fish showed gradual desynchronization to the new phase, taking 7–10 days to be completely re-entrained. Taken together, these results suggest the existence of an endogenous circadian oscillator that controls the expression of locomotor activity rhythms in the Nile tilapia, although its anatomical localization remains unknown.
DOI Link: 10.1080/07420520902926017
Rights: Published in Chronobiology International. Copyright: Taylor & Francis (Informa Healthcare). This is an electronic version of an article published in Chronobiology International, Volume 26, Issue 4, May 2009, pp. 666 - 681. Chronobiology International is available online at:

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