According to the mainstream media it’s the southern Great Barrier Reef that has been hit hardest with coral bleaching, and particularly the corals in the Capricorn region that includes Great Keppel Island.   I have a home in Yeppoon, which is just a short ferry ride away, and have been keen to go see for myself, but the weather has been less than idea.

The dive shop on the island has been telling me there is some bleaching, but it’s hard to see because visibility is a problem.  That has been the situation for the last week – since John Abbot and I drove back to Yeppoon from Noosa.

By ‘visibility’ they mean the distance one can see under-the-water.

Yesterday, Friday, I nevertheless caught the ferry across to the island and made my way around to Monkey Beach reef.

Great Keppel Island is located just to the northeast of the mouth of the Fitzroy River, so when there is a lot of wind and particularly a lot of rain, the water can become murky to the extent you cannot see the corals even if they are just, one metres below, which was the situation yesterday.

While the bleaching has been blamed on elevated sea temperatures, which may be the situation, it’s hard to know.

The bleaching could be from freshwater runoff, from the Fitzroy River.  The Fitzroy River drains the single largest area (approximately 143,000 km2) of the Great Barrier Reef catchments and discharges into the largest estuary and then into Keppel Bay. The Keppel Islands within the bay have many fringing inshore coral reefs, including Monkey Bay reef, which are periodically exposed to discharge from the Fitzroy River – and then the corals become invisible even when you are under-the-water.

When I look at the data for Rosslyn Bay marina, just across from the island and around the bay from where I live in Yeppoon, the most remarkable thing is the drop in sea-level at the end of last year, 2023.

Low tides, associated with low sea levels, can also cause more bleaching than usual, particularly if the low tide occur during daylight hours when there is significant incoming solar radiation.

The lower than usual sea levels are perhaps due to the El Nino, with all the water sloshing across to the other side of the Pacific because the trade winds haven’t been blowing as hard as usual.

Sooner or later, I will get back out to Monkey Beach reef, and I will be able to report what I see.  In the meantime, consider subscribing for my irregular email newsletter so that I can keep you in the loop.

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Can anyone find me some location specific up-to-date sea temperature data for anywhere at the Great Barrier Reef?  Not the colour maps, that are variously based on homogenised satellite records.