Daily rhythms of in vitro fertilization in fish

Trabajo presentado en AQUA2018 joined World Aquaculture and European Aquaculture meeting, celebrado en Montpellier (Francia) el 27 de agosto de 2018.Predictable environmental changes (alternation of day/night, tides, lunar phases and seasons) have fostered organisms to develop a biological clock to keep track of time. Fish reproduction, as well as many physiological functions, exhibit rhythmicity to ensure the survival of the offspring. Furthermore, the timely secretion of gonadotropins and sexual steroids is crucial to synchronize spawning and fertilization. Consequently, it should not be surprising a daily rhythm of in vitro fertilization, which could be used to optimize artificial fertilization protocols. The aim of this research is to investigate the existence of daily in vitro fertilization rhythms in zebrafish, as an experimental model, and in Senegalese sole (Solea senegalensis), as a fish species of great interest in aquaculture. To describe daily rhythms in light-dark cycle (LD) we performed in vitro fertilization trials at different times of the day. For zebrafish we performed fertilization at different Zeitgeber Times (ZT0, ZT1, ZT2, ZT3, ZT4, ZT7, ZT15, ZT21, ZT23) with lights on at ZT0 and off at ZT14. For Senegalese sole, we performed similar trials every 4 hours during a 24h LD cycle. The cosinor analysis (p < 0.05) revealed the existence of a statistically significant daily rhythm for in vitro fertilization with a maximum success around the specie-specific natural spawning time (diurnal or nocturnal for zebrafish and sole, respectively). In addition, one way ANOVA also unveiled statistically significant differences between fertilization time points (p