Climate change's coral spawning 'disorder'

corals no longer spawn in sync. Photo Source: Tom Shlesinger
Corals need to spawn with each other in a matter of minutes to reproduce at their best, but some corals are now spawning longer than normal for days or even months. Researchers say climate change is the cause of this previously unknown threat. The results were published in Science.
year, millions of tiny eggs and sperm beams are released across the reef, turning the ocean into a bright underwater "blizzard" sometimes available from space.
they need to lay large amounts of eggs to defeat predators and prevent reproductive cells from becoming too thin in water. Tom Shlesinger and Yossi Loya of Tel Aviv University in Israel believe that missing a few minutes of the window period can lead to less fertilization, while being hours or days late means that individual corals simply cannot be fertilized.
link between global warming and coral bleaching and coral reef mortality has been confirmed, but its effects on coral spawning synchronization have not been well studied.
to study the effects, Shlesinger and Loya compared coral spawning behavior on Red Sea reefs in recent years with historical data from the 1980s.
2015-2018, the two researchers conducted 225 night-time surveys, each for 2.5 to 5.5 hours. They carefully tracked the reproductive signs of the five largest corals.
corals' spawning depends on environmental cues: temperature and daylight patterns can help them determine when they are ready to lay their eggs, while the exact time of night spawning is thought to be triggered by the lunar cycle and prompted by sunset.
in the 1980s, the main breeding season took place between June and September. At the same time, based on the lunar cycle, the breeding season of one coral species is slightly different from that of another. This is thought to help prevent nearby corals from becoming hybrid corals.
, however, the researchers found that in recent years, three of the five coral species studied have lost their tightly arranged spawning windows and do not have patterns consistent with the moon's phase, ocean temperature or wind speed.
seems to reduce the reproductive success rate of coral populations, which have also declined over the years.
researchers believe climate change, heat stress, light pollution and the influx of hormones such as testosterone and progesterone in the water are to blame. (Source: Xu Xu, China Science Daily)
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