Global warming, climate change, all these things are just a dream come true for politicians. I deal with evidence and not with frightening computer models because the seeker after truth does not put his faith in any consensus. The road to the truth is long and hard, but this is the road we must follow. People who describe the unprecedented comfort and ease of modern life as a climate disaster, in my opinion have no idea what a real problem is.
According to the Bureau of Meteorology, it was going to storm on Sunday. Instead, the day broke calm and sunny. And so, Jenn (not me, there is another one) and M-J from Keppel Dive, took a few of us around to the very exposed Wreck Beach facing due east. This is the beach where you can get properly wrecked on Great Keppel Island – as the story goes.
According to the Bureau of Meteorology, it was going to storm on Sunday. Instead, the day broke calm and sunny. And so, Jenn (not me, there is another one) and M-J from Keppel Dive, took a few of us around to the very exposed Wreck Beach facing due east. This is the beach where you can get properly wrecked on Great Keppel Island – as the story goes.
The map at the dive shop, and me.
According to local legends there is gold here, buried somewhere in the sand with a shipwreck, or three.
I found gold by way of a nudibranch, specifically Chromodoris kuiteri.
The tail end of a nudibranch with filaments of gold. Photograph by Jenn Marohasy at Wreck reef on Sunday, April 21.Can you see the nudi, amongst the corals?
Most striking when you drop down to the reef at the northern end of the bay is all the bleaching. It is everywhere at the reefs fringing this island.
There is so much bleached coral along the wall that we swam from the beach east, northern end. Wreck Beach reef, Sunday April 21.
What is not bleached seems to be a particularly dark chocolate brown: it seems much of the coral either has no zooxanthellae or too much.
Plate corals a very dark brown replete with zooxanthellae, contrasted against the stark white branching that is bleached.Contrasting bleached versus dark brown corals, but these perhaps brown from macro algae rather than symbiotic algae.What species of coral is this? It looks a healthy brown with purple tips. Wreck Beach reef, April 21, 2024.
Can someone explain to me how this works, how does the zooxanthellae become toxic to the coral when the water becomes too warm? What is the physical mechanism?
I’m told that it is not a case of the zooxanthellae dying insitu, rather the coral polyps kick them out.
Leaving Wreck Beach reef, for Secret Cove. More about this secret and a shark in Part 4, tomorrow.Trying to remember the name of this fish. There were a lot of them here, and around the headland at Secret Cove.
The colours on the Coral Health Chart are based on the actual colours of bleached and healthy corals. Each colour square corresponds to the concentration of symbiotic algae living in the coral tissue, which is directly linked to coral health.
I was back at John Brewer Reef last week and many of the corals are now dark brown. John Brewer reef has lost its pink, for the moment.
The corals in this section of John Brewer Reef are now very brown, or green, because they are replete with zooxanthellae.
There is a Coral Watch program that was developed at Heron Island by the University of Queensland. The ‘Coral Watch Coral Health Chart’ quantifies the health of a coral according to the intensity of its colour that is considered a proxy for the concentration of zooxanthellae. A report on the status of corals at Heron Island indicates that the corals tend to score between 3 and 4, which is considered healthy.
Dive Master Paul Crocombie holds a Coral Health Chart against a branching Acropora at John Brewer Reef last Tuesday, 3rd October 2023.
According to The Coral Watch website, to score a reef: 1. Choose a random coral and select the lightest area. [Don’t include the growing tip that is usually white.] 2. Rotate the chart to find the closest colour match.
Photographed at John Brewer Reef last Tuesday by Leonard Lim, colour chart held by Paul Crocombe.
3. Record the colour code on a data slate. 4. Select the darkest area of the coral and record the matching colour code. 5. Record the coral type. 6. Continue your survey with other corals. Record at least 20 corals. 7. Submit your data online at http://www.coralwatch.org
Ideally this is done with the chart beside the coral at the reef. But, given the extraordinary quality of the underwater photographs taken by Leonard Lim last Tuesday, and that some include the colour chart held by Paul Crocombe, a Dive Master, Skipper and Owner of Adrenalin Snorkel and Dive, I am attempting some interpretation here, so we might be able to quantify how brown the corals were last week for that patch of reef.
All four colours of the symbiotic algae/zooxanthellae in the Coral Watch Coral Health Chart are shown in this photograph. I calculate the average colour to be 3.7, I would have guessed that it was even higher.Photograph taken at John Brewer Reef on Tuesday 3rd October 2023 by Leonard Lim.I can’t bring myself to write on this photograph, it is so beautiful. Another from John Brewer Reef on 3rd October 2023.
This section of reef, towards the north east, has particularly healthy corals and exceptional coral cover. There are some sections of John Brewer reef that are all coral rubble. Coral cover and coral colour varies with the particular habitat. Different habitats include reef crest, reef front and back lagoon.
I first visited John Brewer reef on 10th April last year, with photographer Leonard Lim and cinematographer Stuart Ireland, specifically to photograph and film the bleaching. At the time this reef, John Brewer Reef, was reportedly the centre of a sixth mass coral bleaching – and I wanted it all recorded, for that moment in time.
We did find some corals that had bleached white, but mostly I was surprised at how pink the reef was back then. Leonard took some exquisite photographs and Stuart filmed sections of coral that can be viewed in part 1 of a documentary entitled ‘Bleached Colourful’.
The same section of reef, but quite a different colour in April 2022.
Back in April 2022, many of the corals had ‘kicked out’ their symbiotic algae and so it was possible to see more of their natural pink colour. The pink is from a florescent protein that can ‘upregulated’ when corals are stressed.
It is somewhat counter intuitive that the more symbiotic algae, also known as zooxanthellae, the healthier a coral and the less colourful!
According to the Coral Watch Website:
“The Coral Health Charts are based on the actual colours of bleached and healthy corals. Each colour square corresponds to a concentration of symbionts contained in the coral tissue. The concentration of symbionts is directly linked to the health of the coral. All you have to do is match the colour of the coral with one of the colours on the chart. You then record the lightest and darkest colour codes, along with coral type, on a waterproof data slate.
The hues on the chart represent the most common colours of corals, and help our eyes to make an accurate match. The brightness of the colours ranging from 1 to 6 are the same on every side of the chart, so you can mix and match sides.
How beautiful and brown is this coral, photographed at John Brewer Reef last Tuesday.Another Leonard Lim photograph from last Tuesday.What a special coral reef: John Brewer Reef with Paul Crocombe, photographed by Leonard Lim on 3rd October 2023.Every photograph shows something different.
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Stuart, Leonard and Jen at Heron Island in November 2021; I forgot to get a selfie during the recent trip to John Brewer.
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