Coral Spawning on the Great Barrier Reef, just off Port Douglas
November... the temperature is rising and every year around this time the annual coral spawning on the Great Barrier Reef is expected. This event can never be completely predicted when it will actually occur and on which night it will happen.
Coral spawning is initiated at night and is a remarkable event. Approximately 6 months before the coral spawning the coral reefs are starting to get ready. There is a particular script for coral spawning; the water has to be a minimum of 27 degrees, it has to happen 2 to 6 days after a full moon and lastly there should be little tide movement.
The first sign to look out for are the coloured eggs inside the female polyps, they will be just showing through the transparent tops of the polyps. A whole coral colony can release their eggs in minutes and the male polyps release their sperm in that timeframe too.
This is really the start of breeding season on the Reef. Parrot fish, damsels, wrasse are joining the party with dance rituals to attract the females. Trigger fish are starting to behave very protective of their surroundings, Trigger fish earn their name as divers most likely will discover, as they start building nests and protect their home.
Even Giant clams, who look so stoic, will be part of it by setting off a separate clam-spawning event. One starts and other clams follow suit. This time of the year is called 'Sex on the Reef' for these very reasons.
Because all the corals work together they increase the chance of surviving fertilized eggs by saturating the predators with food. Going out to snorkel or dive is special this month because of the extra 'fish food' that is around.
Note: coral spawning 2009 occurred November 4.
