Originally Posted at Jennifer Marohasy’s Blog
Jennifer Marohasy
It’s all the news, right around the world: The Great Barrier Reef is being bleached – again. Children can’t sleep at night: not only the war in Ukraine keeps them awake at night, but also our apparent disregard for nature.
Except!
On April 10, 2022, I traveled to the epicenter of the latest declared severe mass coral bleaching, and found a coral wonderland.
There has been some bleaching, particularly around the perimeter of John Brewer Reef – on the sandy seafloor where the Australian Institute of Marine Science (AIMS) surveyed and concluded coral cover is not never more than 30% – but much of John Brewer Reef is still covered in over 80% colorful coral. This high percentage is denied by AIMS because they never surveyed the top of the reef.
This reef, John Brewer Reef, has been described by ABC, The Conversation and The Guardian as one of the worst bleached places. The Guardian uses ABC-like photographs taken from the environmental group WWF.
At John Brewer Reef just yesterday, I swam over the crest – over the top of the reef – and I also swam along the walls that tumble to the sandy seafloor.
I’ll show you some snapshots that I took with the Olympus TG6, without the lights. I also swam around the sand perimeter, and I’ll show you these photos in my next blog post – which will be Part 2 of this series. In Seasons 3 and 4, I plan to show you a video of the crossings that will happen over the weekend when I return to John Brewer Reef with one of Australia’s best underwater cinematographers.
John Brewer Reef is 70 km (38 nautical miles) east of Townsville, part of the central part of the Great Barrier Reef. Rising from the sandy seafloor are two giant flat, fused limestones that represent layer upon layer of dead coral (which you can’t see) with a top layer (which you can see) of corals. Colorful plates and lots of small fishes. Running between these two reefs is a deep canyon with walls of more coral and more fish.
While most reef apex corals are healthy, some are bleached white and others are brightly bleached.
The pink to purple coloration in some reef apex corals is not due to Zooxanthellae, a symbiotic algae, but to an increased pigment accumulation from the coral itself when Zooxanthellae animals are expelled. Zooxanthellae are expelled when corals are stressed by water that is too hot or too cold. These colorful corals are often described as fluorescing.
******** The photo at the top of this blog post was taken just yesterday (April 10, 2022) when I (Jennifer Marohasy) swam on top of John Brewer Reef. The coral in the foreground is not bleached but has a natural beige color and white tip. Coral pink in the center of the photo is ‘colorful bleached’. The pink to purple coloration in some reef apex corals is not due to Zooxanthellae, which is a symbiotic algae, but to an increased pigment accumulation from host tissue/the coral itself when Zooxanthellae is expelled. This is often referred to as fluorescence and/or multicolor bleaching.
The reef crest corals at John Brewer Reef are bleaching multicolor/fluorescent with full recovery.
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