Environmental factors explain spawning day deviation from full moon in the scleractinian coral Acropora

Abstract

Broadcast-spawning scleractinian corals annually release their gametes with high levels of synchrony, both within and among species. However, the timing of spawning can vary inter-annually. In particular, the night of spawning relative to the full moon phase can vary considerably among years at some locations. Although multiple environmental factors can affect the night of spawning, their effects have not been quantitatively assessed at the multi-regional level. In this study, we analysed environmental factors that are potentially correlated with spawning day deviation, in relation to the full moon phase, in Acropora corals inhabiting seven reefs in Australia and Japan. We accordingly found that sea surface temperature and wind speed within one to two months prior to the full moon of the spawning month were strongly correlated with spawning day deviations. In addition, solar flux had a weak effect on the night of spawning. These findings indicate that Acropora have the capacity to adjust their development and physiology in response to environmental factors for fine-tuning the timing of synchronous spawning, thereby maximizing reproductive success and post-fertilization survival.

Southwestern Atlantic reef-building corals Mussismilia spp. are able to spawn while fully bleached

“…used in this study. Coral spawning during or after bleaching recovery have been observed in the Indo-Pacific (Ward et al 2000;Cox 2007;Dajka et al 2019;Sakai et al 2020) and the Caribbean (Levitan et al 2014;Hagedorn et al 2016;Fisch et al 2019), however, this is the first report demonstrating the ability of corals to spawn and form viable larvae while fully bleached. The bleaching condition was assessed through the color reference chart and it did correspond to low symbiont concentrations.…”

An Indo-Pacific coral spawning database

“…Knowledge of the timing of spawning is also essential for accurately estimating levels of connectivity among populations, given season differences in current flow 14 . The value of long-term species level data on coral spawning has recently been demonstrated in a test of the influence of temperature and wind on the night of coral spawning 15 .…”

A coral spawning calendar for Sesoko Station, Okinawa, Japan

“…3) with spawning occurring earlier relative to the full moon the later the calendar date of the full moon. This pattern has recently been shown to be influenced, in part, by environmental conditions in the weeks and months prior to spawning, in particular, cumulative sea temperatures (Sakai et al 2020).…”