One of the most spectacular events to occur on the Great Barrier Reef is the annual synchronised spawning of corals which has been described as the ‘world’s largest orgasm on the world’s largest organism.’
It was in our very own Geoffrey Bay in 1981 where scientists first discovered this phenomenon and forever changed some of the major concepts in coral reef study, sparking a wider understanding of the reef. Their research was first reported in the Journal Science in 1984, with the following 10 years of research leading to the awarding of the prestigious Eureka Prize for Environmental Science to Peter Harrison and his James Cook University Team in 1992.
This mass reproduction only happens once a year. It involves colonies and species of coral polyps simultaneously releasing tiny egg and sperm bundles from their gut cavity into the water. When an egg meets a sperm it forms coral larva called a planula. This floats around in the water before settling on the ocean floor days or weeks later. The coral colony develops from the settled planua.
The spawning lasts from a few days to a week, and occurs after a full moon usually in spring after rising water temperatures have stimulated the maturation of the gametes. It only happens at night and resembles a multicoloured snowstorm. Different corals spawn at different times depending on their locations, with the inshore reefs usually spawning one to six nights after the full moon in October, and the outer reefs spawning during November to December. It is one of the highlights of the Great Barrier Reef Calendar.
It was here on Magnetic Island that it was first observed and filmed. Since then scientists from around the world have come to Magnetic Island in October to November to study this event. This research has advanced our knowledge of coral responses to cyclones, bleaching, climate change and provided insights into improved management and care of our reefs. In so many ways, our little island is very very special.