#UNDER THE DARK MOONLIGHT FULL#

The effect is stronger and more nuanced in our latest study, most likely because the waters in the tropics are comparatively clear. We evaluated effects of the Moon on growth of larval temperate fish in an earlier study and found a similar effect (moonlight enhanced growth).Ĭoral reefs: climate change and pesticides could conspire to crash fish populations The suppressive effect of moonlight on this movement of potential predators and prey is also a global phenomenon. This is because the nightly upward movements of deep-water animals is ubiquitous - it is the largest mass migration of biomass on the planet, and it happens everywhere. We think this will have implications around the world, not just in the tropics. This makes the incorporation of moonlight into existing fisheries management models relatively simple. But our findings to date are good news for those working to strengthen fisheries management, given that phases of the Moon are predictable and cloud cover that can modify moonlight is being measured by satellites. More research is needed to quantify these lunar effects on other marine populations.

#UNDER THE DARK MOONLIGHT FULL#

On the other hand, during the Full Moon, when surface waters are well-lit, the movement of prey and predators may be suppressed, reducing the risk to the fish but also eliminating their food. In contrast, around the first Quarter Moon, prey are suppressed but predators are not, leading to the slowest growth.ĭuring the New Moon, when the surface waters remain dark throughout the night, influxes of both prey and predators may be high, with the latter preventing the larval fish from enjoying the increased numbers of prey. Thus, larval fish grow best when their predators are absent but their prey are abundant - around the last Quarter Moon. Proceedings of the Royal Society B, Author providedĪs a consequence, prey availability for sixbars in surface waters may be hindered by early nocturnal brightness while the arrival of predators may be impeded by late nocturnal brightness. We found that on the best nights of the lunar month for sixbars, around the last Quarter Moon when the Moon rises around midnight, larval fish grew about 0.012mm a day more than average.īut on the worst nights, around the first Quarter Moon when the Moon is overhead at sunset and sets around midnight, they grew about 0.014mm a day less than average.įour graphs showing the larval fish (in yellow) and the amount of predator (red shading area) and prey (brown shading area) rising to the surface during each phase of he Moon. Their growth appears to be maximised when the first half of the night is dark and the second half of the night is bright.Ĭloudy nights obscure the Moon, and thus allowed us to check our models by contrasting growth on cloudy versus clear nights, which confirmed the effect of moonlight on growth of these fish. The viral ‘Wellerman’ sea shanty is also a window into the remarkable cross-cultural whaling history of Aotearoa New Zealand In our research we found the daily growth rates of the larvae of sixbar wrasse ( Thalassoma hardwicke) around the island of Mo’orea, in French Polynesia, are strongly linked to phases of the Moon. In the past we failed to take into account the influences the night may have on fish development.

Author?, Author provided When the Sun goes down Te Herenga Waka-Victoria University of Wellington provides funding as a member of The Conversation AU.Īdult sixbar wrasse in courtship. Te Herenga Waka - Victoria University of Wellington provides funding as a member of The Conversation NZ. University of Melbourne provides funding as a founding partner of The Conversation AU. Suzanne Alonzo receives funding from the Marsden Foundation and the US National Science Foundation Partners Stephen Swearer receives funding from Royal Society of New Zealand Marsden Fund. Osenberg receives funding from the US National Science Foundation. Jeffrey Shima receives funding from Royal Society of New Zealand Marsden Fund.Įrik Noonburg, a retired Associate Professor of Biological Sciences at Florida Atlantic University,Ĭraig W. Professor of Ecology & Evolutionary Biology, University of California, Santa Cruz Professor of Marine biology, The University of Melbourne Professor of Ecology, University of Georgia Professor of Ecology, Te Herenga Waka - Victoria University of Wellington

Under the dark moonlight