Moonrise timing is key for synchronized spawning in coral Dipsastraea speciosa

Synchronized mass coral spawning typically occurs several days after a full moon once a year. It is expected that spawning day is determined by corals sensing environmental change regulated by the lunar cycle (i.e., tide or moonlight); however, the exact regulatory mechanism remains unknown. Here, we demonstrate how moonlight influences the spawning process of coral, Dipsastraea speciosa. When corals in the field were shaded 1 and 3 d before the full moon or 1 d after the full moon, spawning always occurred 5 d after shading commenced. These results suggest moonlight suppresses spawning: a hypothesis supported by laboratory experiments in which we monitored the effects of experimental moonlight (night-light) on spawning day. Different night-light treatments in the laboratory showed that the presence of a dark period between day-light and night-light conditions eliminates the suppressive effect of night-light on spawning. In nature, moonrise gets progressively later during the course of the lunar cycle, shifting to after sunset following the day of the full moon. Our results indicate that this period of darkness between sunset and moonrise triggers synchronized mass spawning of D. speciosa in nature.

An Indo-Pacific coral spawning database

The discovery of multi-species synchronous spawning of scleractinian corals on the Great Barrier Reef in the 1980s stimulated an extraordinary effort to document spawning times in other parts of the globe. Unfortunately, most of these data remain unpublished which limits our understanding of regional and global reproductive patterns. The Coral Spawning Database (CSD) collates much of these disparate data into a single place. The CSD includes 6178 observations (3085 of which were unpublished) of the time or day of spawning for over 300 scleractinian species in 61 genera from 101 sites in the Indo-Pacific. The goal of the CSD is to provide open access to coral spawning data to accelerate our understanding of coral reproductive biology and to provide a baseline against which to evaluate any future changes in reproductive phenology.

First record of synchronous coral spawning in a marginal coral community in Shenzhen, China

Here we present the first documentation of a synchronous coral spawning event in a marginal coral community in Shenzhen. Acropora pruinosa was observed spawning for seven consecutive nights after the full moon, and Platygyra carnosa was observed spawning on the eighth and ninth nights after the full moon.

How Does the Sexual Reproduction of Marine Life Respond to Ocean Acidification?

Recent research indicates that synchronicity of sexual reproduction in coral spawning events is breaking down, leading to aging populations and decreased recruitment success. In this perspective, we develop a hypothesis that this phenomenon could be caused by ongoing ocean acidification (OA). We hypothesize, that the underlying physiological machinery could be the carbon concentrating mechanism (CCM). The endosymbiotic zooxanthellae of corals could use this mechanism to sense calm water motion states in a comparable way to that known from macroalgae. In macroalgae, it is well-established that dissolved inorganic carbon (DIC) acts as the trigger for signaling low water motion. Hence, evolutionarily developed signals of low water motion, suited for gamete-release, may be misleading in the future, potentially favoring opportunistic species in a broad range of marine organisms.

BROADCAST SPAWNING PATTERN AND PELAGIC LARVAE DURATION OF ACROPORA CYTHEREA AND A. CLATHRATA FROM INSHORE REEF AREA IN KUANTAN COASTAL REGION

Acropora sp. is the second-most abundant among the coral genera in the Kuantan coastal region (KCR) located on the east coast of Peninsular Malaysia. This study investigated the timing of coral spawning of two Acropora species; Acropora cytherea and Acropora clathrata through dissection and histological analyses of coral fragments that were collected during predicted spawning months (March until May 2018) from Balok reef, Kuantan. Histological results showed the presence of mature oocytes from a sample collected in April and May 2018, which indicate an extended gamete release pattern for these species within KCR. The gamete maturity coincided with the peak sea surface temperature within KCR from April until May. Both Acropora species spawned between 10-11 nights after the full moon. Present results also indicated that both Acropora species have optimal pelagic larvae duration (PLD) between 6 – 8 days after spawning. This study contributed to the limited knowledge of coral reproductive biology on the east coast of Peninsular Malaysia. In addition, the timing of coral spawning provides valuable data for population connectivity modelling.