title: Synchronization to light and mealtime of the circadian rhythms of self-feeding behavior and locomotor activity of white shrimps (Litopenaeus vannamei).
abstract: The role of light and feeding cycles in synchronizing self-feeding and locomotor activity rhythms was studied in white shrimps using a new self-feeding system activated by photocell trigger. In experiment 1, shrimps maintained under a 12:12h light/dark (LD) photoperiod were allowed to self-feed using feeders connected to a photoelectric cell, while locomotor activity was recorded with a second photocell. On day 30, animals were subjected to constant darkness (DD) for 12days to check the existence of endogenous circadian rhythms. In the experiment 2, shrimps were exposed to both a 12:12h LD photoperiod and a fixed meal schedule in the middle of the dark period (MD, 01:00h). On day 20, shrimps were exposed to DD conditions and the same fixed feeding. On day 30, they were maintained under DD and fasted for 7days. The results revealed that under LD, shrimps showed a clear nocturnal feeding pattern and locomotor activity (81.9% and 67.7% of total daily food-demands and locomotor activity, respectively, at nighttime). Both feeding and locomotor rhythms were endogenously driven and persisted under DD with an average period length (τ) close to 24h (circadian) (τ=24.18±0.13 and 23.87±0.14h for locomotor and feeding, respectively). Moreover, Shrimp showed a daily food intake under LD condition (1.1±0.2gday(-1) in the night phase vs. 0.2±0.1gday(-1) in the light phase). Our findings might be relevant for some important shrimp aquaculture aspects, such as developing suitable feeding management on shrimp farms.
authors.affiliation: Laboratory of Fish Nutrition and Feeding Behaviour (AquaUFRB), Faculty of Fishing Engineering (NEPA), Center of Agricultural Science, Environmental and Biological (CCAAB), University of Bahia (UFRB), 44380-000 Cruz das Almas, Brazil.
authors.forename: Aline Dos Anjos
authors.initials: ADA
authors.lastname: Santos
authors.affiliation: Department of Physiology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, 30100 Murcia, Spain.
authors.forename: José Fernando
authors.initials: JF
authors.lastname: López-Olmeda
authors.affiliation: Department of Physiology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, 30100 Murcia, Spain.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Sánchez-Vázquez
authors.affiliation: Laboratory of Fish Nutrition and Feeding Behaviour (AquaUFRB), Faculty of Fishing Engineering (NEPA), Center of Agricultural Science, Environmental and Biological (CCAAB), University of Bahia (UFRB), 44380-000 Cruz das Almas, Brazil. Electronic address: fortes@ufrb.edu.br.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Fortes-Silva
mesh_terms: D000818:Animals; D017756:Aquaculture; D002940:Circadian Rhythm; D003624:Darkness; D004435:Eating / Q000502:physiology / Q000528:radiation effects; D005247:Feeding Behavior / Q000502:physiology / Q000528:radiation effects*; D008027:Light; D008124:Locomotion / Q000502:physiology / Q000528:radiation effects; D009043:Motor Activity / Q000502:physiology / Q000528:radiation effects*; D033561:Penaeidae / Q000502:physiology / Q000528:radiation effects*; D017440:Photoperiod; D013997:Time Factors
keywords: Biological rhythms; Circadian rhythm; Endogenous clock; Feeding schedules; Self-feeding