Locomotor, feeding and melatonin daily rhythms in sharpsnout seabream (Diplodus puntazzo)

Citation

Vera L, Madrid JA & Sanchez-Vazquez FJ (2006) Locomotor, feeding and melatonin daily rhythms in sharpsnout seabream (Diplodus puntazzo). Physiology and Behavior, 88 (1-2), pp. 167-172. https://doi.org/10.1016/j.physbeh.2006.03.031

Abstract
Sharpsnout seabream is a marine teleost of increasing interest for Mediterranean aquaculture, but there is still a lack of information regarding its circadian organization. In this study, we have investigated sharpsnout seabream locomotor activity, feeding and plasma melatonin daily rhythms under a 12:12-h LD cycle, as well as the persistence of locomotor activity circadian rhythmicity under constant light (LL) conditions. When submitted to an LD cycle, most sharpsnout seabream displayed a diurnal locomotor pattern, with an average 74% of activity recorded during daytime. However, along the experiment 40% of fish spontaneously changed their locomotor rhythm phasing and became nocturnal. Feeding behaviour, nevertheless, remained strictly diurnal in all cases, with 97% of food demands being made during the light period. Free-running locomotor rhythms were recorded in one third of the fish kept under LL. Daily plasma melatonin levels displayed a rhythmic profile, with low daytime values (111 pg/ml) and high nighttime concentrations (791 pg/ml). Taken together, these results evidence a high degree of plasticity for sharpsnout seabream activity patterns, as well as phasing independence of locomotor and feeding rhythms. Finally, the existence of a well-defined daily rhythm of plasma melatonin was found.

Keywords
sharpsnout seabream; locomotor activity; feeding behavior; melatonin

Journal
Physiology and Behavior: Volume 88, Issue 1-2