Great Barrier Reef spawning event brings hope for heavily bleached coral

The Great Barrier Reef’s huge spawning event gives hope to revitalising the struggling reef… thanks, Billie Eilish?

Reef Teach scientists recorded the coral erupting with life on Tuesday, just after Billie Eilish allowed CoralWatch to use her hit song Ocean Eyes in campaigns to save the reef. Coincidence? Yeah, look, probably.

The coral is fertilising offspring by casting sperm and eggs into the Pacific Ocean just off the coast of Cairns. It’s predicted trillions of eggs and sperm have been released into the ocean so far, with scientists hoping that this year’s reproductive cycle can help regenerate bleached parts of the world’s largest reef.

Image: AAP

The Great Barrier Reef consists of 2,500 reefs that cover more than 348,000 square kilometres, which have seen significant levels of bleaching due to rising ocean temperatures. This bleaching has caused damage to over two-thirds of the coral, with five major bleaching events in the last 20 years, (most recently 2016, 2017 and 2020).

Earlier this month, a study from James Cook University in Australia found that only two percent of the reef had escaped bleaching since 1998.

For much of the year, coral multiplies through splitting and dividing, but once a year the coral simultaneously releases bundles of sperm and egg into the ocean.


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A post shared by Reef Teach Cairns Australia (@reefteach)

The conditions have to be just right for the reef to erupt like this. It only happens at night, a few days after a full moon, with calm waters and water temperatures above 26 degrees for a full month – which sounds a bit like a tropical honeymoon.

Spawning events such as these generally only last between two to three days, usually between October to November, but timings can vary due to factors like water temperature and currents.

The date of the spawn can also fluctuate across the length and breadth of the reef.

This may be a sign of hope towards a much needed rejuvenated reef, especially with other concerning ecological issues in our country like what’s shown in our performance in climate reports.

As we said, the spawning event falls suspiciously close to Billie Eilish joining the fight to help the reef and while we know the song Ocean Eyes is a hit, it’s great to see the struggling coral reef thinking it’s a banger too.