World will watch as Barrier Reef gets amorous
The world’s largest synchronised sex event, filmed every year on a moonlit night in the tropics, is to be live-streamed for the first time.
Corals in the Great Barrier Reef are expected to release trillions of eggs and sperm cells into the water this weekend, triggered by early full moons in the Australian summer.
The event has been likened to a vast underwater snowstorm, with watery clouds of white, pink and red changing the colour of the sea throughout the 133,000 square miles of reef.
When a coral sperm and egg meet they form larvae, which settle and create polyps. Scientists are hoping for a bumper spawning this year, to repair some of the damage that warming waters have done to the reef, which at nearly 2400 kilometres long is the earth’s largest living structure.
It has been designated a World Heritage site by Unesco.
The mass spawning event, which lasts three or four nights and began last night, happens annually across the 3000 coral reefs and 600 islands that make up the Great Barrier Reef off the northeast of Australia.
ABC, the Australian national broadcaster, plans to stream the event live, using remote camera vehicles both above and below the water, with teams of experts and production staff linked by satellite at either end of the reef 2400km apart.
The broadcast has been a year in the planning.
But live performers cannot always be relied upon. About one year in 10 the spawning does not happen when predicted, as the coral responds to subtle changes in the environment.
Scientists only became aware of the mass spawning in 1981. Before that it was thought that corals brooded and released fertilised embryos all year round. Researchers have since identified three natural conditions that must coincide for the corals to begin releasing their trillions of eggs and sperm cells into the water.
The first trigger is a sharp rise in water temperature as summer begins. A second trigger is moonlight, to which coral tissues are highly sensitive. Spawning occurs between four and seven nights after a full moon. Finally, the event must happen at night, when fewer predators are around to feast on the embryos and lipidrich spawn. Some corals spawn at dusk and others up to an hour after sunset.
Last summer the reef was hit by coral bleaching, which happens when the water becomes too warm. The corals expel the algae that live in their tissues and as a result turn completely white. Some do not recover. The condition of the Great Barrier Reef has been downgraded from ‘‘significant concern’’ to ‘‘critical’’, according to a recent report compiled for Unesco. The International Union for Conservation of Nature switched to its most serious rating, indicating that the reef’s very existence is now under threat from climate change. – The Times