A three-year study has uncovered new details about coral reproduction, revealing hormonal cycles similar to those of humans and other animals, as well as a new way to detect reef distress before it is too late.
Corals simultaneously release their eggs and sperm into the sea once a year. However, what happens in months preceding That timing has largely remained a mystery.
In a new one, published in iScienceresearchers discovered evidence that corals may rely on hormonal cycles similar to those used by many animals. including humans, to prepare for the reproduction.
According to , scientists monitored reproductive hormones in corals Red Sea over three consecutive years.
The findings reveal a hidden biological rhythm which could help explain how corals coordinate reproduction and how scientists can detect reproductive stress before spawning failures become visible.
“Corals reproduce with incredible synchronization. We know what environmental stimuli are involved, but we wanted to understand the coral’s internal signals that maintain this synchronization”, explained the first author of the study, Chen Azulay.
Scientists focused on the species Acropora eurystomafound no Gulf of Aqabaa region often described as a potential refuge in the face of warming oceans.
By collecting samples of corals throughout their reproductive cycle, between 2021 and 2023, the team produced the first multi-annual registration of the dynamics of steroid hormones during the development of coral gametes.
Estrogen levels have been observed to peak several months before spawning, during the early stages of egg development, progressively decreasing as they mature.
In turn, progesterone remained relatively stable throughout the breeding season, but recorded a sharp increase several months after spawning, suggesting it could help initiate the next reproductive cycle.
Scientists also observed that sunlight was the main determining factor these hormonal levels. Over the years of the study, day length and ultraviolet radiation have proven to be more reliable indicators of estrogen levels than seawater temperature.
They also found that hormone levels were evenly distributed throughout the colony, but that the central areas of the corals were more likely to contain developing ovules than the outer growing ends.
This finding suggests that local conditions within a colony, such as age, energy reserves or developmental stagecan determine which polyps respond to reproductive signals.
The researchers say that future studies will analyze whether similar hormonal cycles occur in other species and in reefs from different regions of the world. If this hypothesis is confirmed, the work could redefine scientific understanding of coral reproduction and provide a new tool for reef conservation.
