From Jennifer Marohasy

By jennifer 

Last Wednesday, after diving Wheeler, Lynch and Chicken reefs we made it to Davies.  I particularly wanted to visit this reef as the Australian Institute of Science (AIMS) has a weather station here at Davies.

Stuart put his drone up and got photographs of the weather station and its immediate surrounds.

There is no evidence of recent bleaching from this aerial photograph, but rather patches of reef that appear to have been lost to brown algae.   It looks devastating from the air, the extent of the infestation of algae.

AIMS records temperatures at different depth at some reefs with the temperature data for Davies at a depth of 4 metres extending back to 1991, providing 33 years of information on water temperatures. The warmest summer in this record is in the year 2020.

AIMS also collects water temperature data down to 18.5 metres at Davies. This data also shows temperatures cycling within an approximate 6C range.   This data does not suggest that this summer has been particularly warm – at least not in this central region relative to the last 18 summers, which is the extent of the publicly available temperature record at this depth for Davies reef.

Water temperature data collected by AIMS at a depth of 18 metres, showing very marked changes with each season, showing cycles of warming and cooling.

This summer at Davies, temperatures don’t appear to have got unusually warm – with the time series data from both 4 metres and 18.5 metres extending right up to 28^th March 2024; right up until the end of summer and some.

Yet the reef crest, at Davies, as for Lynch, was looking devastatingly bare.

Tropical cyclone Kirrily hit on 25^th January; nearly 10 weeks ago.  It has scoured the shallow flat top of this reef, and it seems also the wall.

As there is no coral, presumably following pummelling by the cyclone, specifically TC Kirrily, well, there is nothing to bleach.

At some depth it is the well attached corals that have survived and show some bleaching.

Amazingly, we did find some large healthy plate corals at a different section of the reef crest that have survived, and they are a good dark brown meaning they are replete with zooxanthellae.

This  clip that Stuart filmed shows these large brown plates at the crest of Davies, on Wednesday 3^rd April 2024.

How did these large plates manage to avoid being smashed into chunks, and then swept over the edge by TC Kirrily?

Perhaps because there is not much coral left, the extent of damage from coralliferous fishes, perhaps bump head parrot fish, seems severe.

We only had time to dive the northwest of this reef, with less than an hour in the water.

Hopefully there are other sections with more coral – hopefully there are other sections less affected by TC Kirrily.

As I posted at my Facebook page earlier today: there are two types of scientists, those who try and make their observations fit the narrative and those who let the data speak for itself. I am a fan of the latter; I seek information about the natural environment not to confirm my prejudices, but to learn about nature.

We can’t know whether this section of the Great Barrier Reef is suffering from global warming or cyclone damage, if we aren’t prepared to get into the water and make some observations.

I am a huge fan of 19th century British biologist Thomas Huxley. Back in 1860 he wrote:

My business is to teach my aspirations to conform themselves to fact, not to try and make facts harmonise with my aspirations. Science seems to me to teach in the highest and strongest manner the great truth which is embodied in the Christian concept of entire surrender to the will of God. Sit down before each fact as a little child, be prepared to give up every preconceived notion, follow humbly wherever and to whatever abysses nature leads, or you shall learn nothing. I have only begun to learn content and peace of mind since I have resolved at all risks to do this.”

It is the case that the corals in the central region of the Great Barrier Reef appear to have been more impacted by TC Kirrily, than warmer than average water temperatures.

This is my observation, supported by the available water temperature data for Davies reef; the AIMS data.

I’m very grateful to Adrenalin Dive for the opportunity to visit this reef, and to the Institute of Public Affairs for funding this adventure.  The video and photographs are by Stuart Ireland.  Stuart has passed me the raw footage, that I have posted clips and snippets of here.  There will be a short documentary, with much more information and interviews soon.

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The feature image (at the very top of this post) shows me/Jennifer Marohasy swimming while holding my breath.  Following is Paul Crocombe on scuba, blowing bubbles.  The photograph is a screenshot from video taken under-the-water by Stuart Ireland.  (I was on snorkel/free diving all day on Wednesday.)

And a last photograph of the boat taken on my Olympus TG6, when I came up for air.   The water really was that blue, at Davies Reef last Wednesday.