Where Corals Spawn

An amazing natural phenomenon that sees millions of tiny cells spewing out of effervescent living corals, this annual event is too good to pass up. We trace the triggers that set off spawning at distinctive times around the world.

1.FLOWER GARDEN BANKS NATIONAL MARINE SANCTUARY, GULF OF MEXICO

7–10 nights following full moon (Aug) The corals coordinate their efforts such that only one species is spawning at a time

2. THE FLORIDA KEYS, US

➢ Aug/Sep after full moon
➢ The Elkhorn coral and Staghorn coral, both protected under the Endangered Species Act, can be seen spawning here

3. CAYMAN ISLANDS, WESTERN CARIBBEAN SEA

➢ Aug/Sep after full moon
➢ Star coral is the most abundant species, with colonies that spawn simultaneously and within a few seconds

4. BOCAS DEL TORO, PANAMA (CARIBBEAN COAST)

➢ 3–9 days after full moon (Sep)
➢ 5–7 days for most common species
➢ Several species spawn at the same time, yet the corals are able to avoid crossbreeding – a phenomenon that is still being investigated

5. GALAPAGOS ISLANDS

➢ Feb–Oct
➢ Despite having been through two bands of warm water (El Niño), which can kill several corals, the reef is now recuperating

6. GULF OF EILAT, RED SEA 

➢ Jun–Sep
➢The majority of corals spawn in summer, when algae populations decline and there is more space on reef flats

7. KENYA, AFRICA
➢ Oct–Apr
➢➢Calm winds allow corals to reproduce before the eggs and sperm disperse, thus corals on Kenya’s coast, which has months of light winds, have long spawning periods

8. MALDIVES
➢ Mar–Apr
➢ It is the norm for mass spawning events to take place in two subsequent months rather than one event a year

9. KOH TAO, THAILAND
➢ Mar
➢ Programmes are in place to capture coral eggs and sperm during spawning, for selective breeding and eventual restoration of the local reefs.

10. SINGAPORE
➢ Mar/Apr after a full moon
➢➢Singapore’s reefs have almost half as many coral species as the Great Barrier Reef, but are only 0.01% its size

11. DONGSHA ATOLL NATIONAL PARK, TAIWAN
➢ Apr
➢➢Formed over 10 million years of reef building, this is the only fully developed coral atoll in Taiwan’s waters

12.OKINAWA, JAPAN
➢ May–Sep
➢ Some species spawn over two or three months, so there is less synchrony, but the Acropora species’ spawning is highly synchronised within the species

13. PALAU ARCHIPELAGO, MICRONESIA
➢ Apr–May
➢ April: Mainly stony coralsspawn
(Acropora, Scleractinia)
➢ May: Mainly non-Acropora corals spawn

14. GUAM, MICRONESIA
➢ About a week after a full moon
(Jul)
➢ Since Guam’s wet season coincides with coral spawning and reduces fertilisation rates, researchers collect eggs to fertilise and culture before transplanting them to the reef

15. HAWAIIAN ISLANDS
➢ Apr–Sep
➢ Hawaii is the only site where certain coral spawning can be observed during the day rather than the typical night phasing

16. NINGALOO, WESTERN AUSTRALIA
➢ On/after full moon night (Mar)
➢ More than 200 species of corals spawn and the waters are filled with brightly coloured polyps

17. GREAT BARRIER REEF, AUSTRALIA
➢ After full moon
(Oct–Nov, inshore reefs)
(Nov–Dec, offshore,
northern, southern reefs)
➢ Mass coral spawning phenomenon (several species spawning simultaneously)
➢ Discovered in 1981

For the rest of this article (Asian Diver Issue 2/2014, Vol.131) and other stories, check out our past issues here or download digital copy here.