Underwater footage captures the moment future generations of coral reef are created on the Great Barrier Reef during recent coral spawning. Matthew Stock reports.
It's one of nature's wonders - the annual coral spawning on the Great Barrier Reef Coral colonies and species simultaneously release trillions of egg and sperm cells for external fertilisation. The event lasts several nights, in the spring and after a full moon, when the conditions are just right. Coral spawning increases distribution of the corals to different areas and increases genetic resilience. This initial spawn saw pleasingly high numbers of egg and sperm cells released, according to marine biologists. That's good news for the reef after recent bleaching events destroyed large swathes of it. Bleaching happens when the water is too warm, forcing coral to expel living algae, causing it to calcify and turn white. Some coral can recover if the temperature drops. Otherwise it may die. Stretching 2,300 km along Australia's northeast coast, the Great Barrier Reef is the world's largest living ecosystem.