Embryonic exposure to artificial light at night impairs learning abilities and their covariance with behavioural traits in teleost fish

The natural light cycle has profound effects on animals’cognitive systems.Its alteration owing to human activities, such as artificial light at night(ALAN), affects the biodiversity of mammalian and avian species by impair-ing their cognitive functions. The impact of ALAN on cognition, however,has not been investigated in aquatic species, in spite of the common occur-rence of this pollution along water bodies. We exposed eggs of a teleost fish(the zebrafishDanio rerio) to ALAN and, upon hatching, we measuredlarvae’cognitive abilities with a habituation learning paradigm. Both controland ALAN-exposed larvae showed habituation learning, but the latterlearned significantly slower, suggesting that under ALAN conditions, fishrequire many more events to acquire ecologically relevant information. Wealso found that individuals’learning performance significantly covariedwith two behavioural traits in the control zebrafish, but ALAN disruptedone of these relationships. Additionally, ALAN resulted in an averageincrease in larval activity. Our results showed that both fish’s cognitive abil-ities and related individual differences are negatively impacted by lightpollution, even after a short exposure in the embryonic stage