Pristine Magnetic Island reefs bouncing back to colour after bleaching
Pristine coral reefs off Townsville were severely damaged by a widespread bleaching event. But to the relief of locals, corals off Magnetic Island are showing signs of recovery.
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Pristine coral reefs off Townsville were severely damaged by a widespread bleaching event which impacted large parts of the Great Barrier Reef.
But to the relief of locals, corals off Magnetic Island are showing signs of recovery.
In February James Cook University PhD student and Magnetic Island resident Blanche D’Anastasi noted widespread bleaching off the island.
She said the typically pristine corals matched some of the best in the world.
“There’s like patches of reef on Magnetic Island that approach 100 per cent coral cover and are as beautiful as many places I’ve dived, like the Coral Sea and even Fiji,” she said.
But hot sea temperatures took a toll during summer.
Retired marine biologist Leon Zann documented the bleaching on a video, saying it was the worst he had seen in 50 years.
The water in summer was unusually clear and more than 30C, which was about 1.5C hotter than usual.
Dr Zann’s video showed bleaching of coral bommies he said were more than 100 years old.
He said the bleaching was worse than the last major bleaching event in 2017.
However there are signs some corals have survived.
Ms D’Anastasi had been snorkelling around Geoffrey Bay in recent weeks and had seen colour begin to return.
“We’re starting to see the colour coming back to the sides,” she said.
“Whilst many colonies, some very old, died because they got fried like eggs in the marine heatwave earlier this year, the survivors are getting their symbiotic algae back and starting to turn from their bleach bone white near death state, back to hues of olive brown, greens, purple and pink.
“I could see these big, old bommies that are between 200 and 2000 years old they’ve managed to survive. Those that made it through the heatwave, they have little cups of coral skeleton. You can see the cups on the underside are turning brown again.”
But Ms D’Anastasi holds concerns for the future of the corals she regards as world class.
“Lots of these corals probably won’t have the resources to make babies in the next couple of years, which is concerning. We can only hope for a kind summer next year free of more marine heatwaves, so that these survivors get a solid year to recovery their energy stores,” she said.
Ms D’Anastasi said the corals were not of the woods yet though and urged people to do their bit to protect them.
“(Now) you can definitely see that our corals have been through a major bleaching event, there’s still a lot of bleaching out there,” she said.
HOW TO STAY REEF SAFE
-by Blanche D’Anastasi
Magnetic Island’s reefs are beautiful, but fragile. Flailing flippers and stressed people standing up on reefs does a lot of damage to the corals on our premier tourism reefs, like Geoffrey and Arthur.
Here are ways that snorkellers and those hiring/loaning gear to tourists and friends can help protect the reef from snorkel damage:
#1 Fit your gear properly, before you hit the water. By doing so you minimise discomfort in the water and could prevent damage to reefs by snorkellers standing on corals to adjust masks or flippers.
#2 Use a floaty. It takes some of the effort out of snorkelling so that you have more energy to enjoy the reef. It also gives you a stable platform for adjusting gear.
#3 Use reef safe snorkel positions. Practice adjusting your gear and changing direction without dropping your feet down. Lift your knees towards your chest and float like a ball while adjusting gear.
#4 Use reef safe fin kicking techniques. Always fin kick gently around reef unless you have a reason to move quickly (e.g. an emergency).
#5 Never snorkel over reef that’s less than 1m deep. Skirt the edge of shallow reef rather than swimming right over the top, because any sudden movement by you, especially if a wave hits you, can push you right into fragile coral, damaging it and potentially injuring you.
Originally published as Pristine Magnetic Island reefs bouncing back to colour after bleaching