MY mother lived and worked on Heron Island at the Great Barrier Reef in 1955. That was the same year the young Bob Endean established the University of Queensland Heron Island Research Station. He went on to become a famous marine biologist, and instrumental in the formation of the Great Barrier Reef Marine Park Authority (GBRMPA) in 1975.
There are photographs of my mother, then Joan Edith Pearce, standing knee deep surrounded by Porites coral micro atolls that are stunted and bleached. I showed one of these at my talk entitled ‘Climate Change Concern’ at the Maroochydore Surf Life Saving Club on 14th July. This has now been made into a YouTube:
The growth of corals back in 1955 at Heron Island was constrained by their inability to continue to grow-up, because sea levels were not rising. This continues to be the situation today — despite what you might to be told on the nightly news.
In fact, a peer-reviewed technical paper by L. Scopelitis et al. published in the journal ‘Coral Reef’ (2011) and rather curiously entitled ‘Coral colonisation of a shallow reef flat in response to rising sea level: quantification from 35 years of remote sensing data at Heron Island, Australia’ explains that the period 2002 to 2007 has been the most constrained for Heron Island corals since at least 1940. This is apparently because they have reached their vertical limit for growth, and there has been no sea level rise.
The single biggest threat to the Great Barrier Reef is sea level fall. Sea levels did fall some 30 centimetres during the recent super El Nino event of 2015/2016 as I explain in the YouTube presentation.
This is not a large amount considering that the tidal range at Heron Island on any one day can be anything from 1 to 3 metres.
But 30 centimetres is enough to result in bleaching of the top 30 centimetres of a coral that may be subject to sunshine on the exposed reef flat for perhaps an hour.
Heron Island is a coral cay that formed perhaps 6,000 years ago, perhaps following a violent storm when a large pile of coral rubble and broken shells was left above the high tide mark. It has grown since then.
The incident of bleaching due to low sea levels associated with El Nino events has been documented at other Great Barrier Reef islands back 3,000 years by Helen McGregor at Wollongong University.
I’m specifically thinking of her paper entitled ‘Coral micro atoll reconstructions of El Nino-Southern Oscillation: New windows on seasonal and inter annual processes’, which was published in the journal ‘Past Global Changes’ (volume 21) in 2013. By dissecting micro-atolls — the type shown in the picture of my mother at Heron Island back in 1955 — it is possible to understand that sea level has been a constraint to coral growth at the Great Barrier reef for at least this long: at least 3,000 years.
The distinctive micro-atoll form is a result of continual exposure to heat and sunlight at extremely low tides, which result, of course, in low sea levels.
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I’m leaving Noosa tomorrow for the Great Barrier Reef. If you would like to be updated on my work there — with a drone pilot and underwater photographer — considering subscribing for my irregular email updates:https://jennifermarohasy.com/subscribe/
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Thanks for your enlightening empirical explanation of the facts.
So refreshing compared with the extrapolation from tenuous speculative data so frequently relied on as grounds for the claimed imminent and inevitable ‘catastrophic’ destiny of the developed world.
The sea level is falling or perhaps the land is slowly uplifting?
Sea-level changes are dependent on (a) knowing whether the land where the measurements are taken is static, rising or subsiding and true rise or fall of the sea level which is subject ocean currents, temperature, wind direction and atmospheric pressure. Along the southern coast of Namibia where diamond mining has occurred on raised beaches accurate levels surveying of the 6000-8000yr old 2 metre beach show that over a 30 miles length of coastline crustal warping has raised sections of the wave-cut platform whilst some parts remained static and some parts subsided. This beach is in an area which is regarded as a stable crustal area. When a series of sea-level stations are considered sea level rise has been a steady 2.8mm per annum for the past 150yrs. I suggest that Heron Island is on a gently rising sea floor perhaps 3-4mm per annum.
> ” … with a drone pilot and underwater photographer”
Great.
I love empirical exploration – all geos do.
Looked like you were having fun in that great video Jennifer. I wonder if the potholes there will be de-platformed for being politically incorrect geology? Interesting to see the 18.6 year cycle and the sea levels being so well explained. One day i hope to be able to see if one of the twice daily low tides were synchronising with the warmest and sunniest times of day during that “event”.
As a geologist I often wonder how coral reefs such as Heron Island have reacted to the natural sea level variation of +/- 2-4m over the last 8,000 years (both above and below current MSL), and then to the more than 100m dramatically lower level before that, during the last ice age.
The answer has to be that corals grow and fall (die) to a level close to what ever the sea level is at the time, probably reacting quickly (geologically).
Heron Island and nearby reefs are coral structures (small hills) that sit on an effectively horizontal plain some 40-60m below current MSL.
The sea levels of the Holocene Highstand, about 4-6,000BC or 6-8,000 years ago were 2-4m above todays levels. Little evidence of corals that grew up to those higher sea levels remain on Heron Island or other inner coral cays; they have been eroded away.
At the peak of the last ice age, approx 20,000 years ago, none of the inner Barrier Reef corals such as Heron Island existed – the area was dry land.
The corals grew as the great global ice sheets melted and the Holocene sea transgression occurred, as the earth moved to a warmer climate (naturally).
Such an interesting insight.
The catastrophist coalition has much to answer for.
What a coincidence! I spent two weeks on Heron Island in August 1953. But I don’t remember anything much about the state of the coral. But I did have a most enjoyable romantic encounter … I was17 at the time. Cheers,
Don