It’s one of the most remarkable natural phenomenon’s on our planet and ensures the future of our coral reefs. Only a small number of people have witnessed coral spawning on the Great Barrier Reef which has been described as a spectacular, coordinated frenzy. And this year is even more special with a ‘spilt-spawning’ occurring at inshore reefs at Geoffrey Bay, Magnetic Island.
What is coral spawning?
Every year corals simultaneously reproduce by releasing millions of tiny egg and sperm bundles into the water. The egg or sperm bundles rise to the surface and must come into contact with the same species in order to fertilise and reproduce. Fertilised eggs develop into larvae which, once matured, settles on the ocean floor and grows into coral. By mass spawning it increases the likelihood of successful fertilisation between eggs and sperm of the same species. Not all coral larvae survives because it is eaten by other marine animals like fish and plankton or washed out to sea.
DID YOU KNOW?
This year marks the 40th Anniversary of the discovery of coral spawning. It was at Geoffrey Bay on Magnetic Island where Professor Peter Harrison witnessed the mass spawning, and from that moment forward it transformed scientist’s understanding of sexual reproduction of corals. The first records of multiple species spawning together dates back to October 18 – 21, 1981.
Image credit: Coral Sea Foundation
When does it happen?
Coral spawning relates to the cycle of the full moon, the tides and temperature of the water. It usually happens 2 – 5 days after the full moon in November, however, because the full moon is late in November 2021 and the shallow water close to the coast is already warmer than the waters offshore, the inshore coral reefs on Magnetic Island will spawn twice – this is what is called a ‘split-spawning’. They spawned in October (Saturday 23) and will spawn again in November, after the full moon (Friday 19). Coral spawning only happens at night and generally lasts a few days. According to the CSIRO multiple coral spawning could increase recovery and resilience of the Reef due to there being a more consistent supply of coral larvae in the water.
Image credit: Coral Sea Foundation
Why is coral spawning important?
Coral spawning is incredibly important to the overall survival of reef ecosystems. It helps coral populations regenerate and secures the future of our coral reefs. Without spawning, corals would cease to exist, and because corals are immobile this process allows new individual corals to spread and grow in otherwise uninhabited areas of the ocean. In years where there are ‘spilt-spawning’ events (like this year off the coast of Townsville) it’s incredible news for future coral populations in the region because there’s more chance of reproduction and larvae maturing to the stage where it can grow on the ocean floor.
Want to witness coral spawning?
This awe-inspiring act of nature usually only happens once a year, so if you’re interested in witnessing it for yourself, join our 2022 coral spawning list and we’ll keep you updated on trips and how to book, as it gets closer. Email info@adrenalindive.com.au to register your interest for 2022 trips.
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