coral bleaching at lady musgrave?

It was a very quick visit to Lady Musgrave this time. Rain was approaching in the forecast but we thought we could still squeeze in a few days of the remaining sunshine at one of our favourite anchorages on the coast.

There has been a lot of press about a recent coral bleaching event which occurred over our summer, one that even reached as far as our Southern Great Barrier Reef, which includes Lady Musgrave. This is usually my first snorkel destination when we sail north, so I was very keen to see the impact of the coral bleaching in the Lady Musgrave lagoon.

The entire Great Barrier Reef on the Queensland coast, all 2,300 km of it, had been impacted by this coral bleaching event. There have been four mass bleaching events in the Great Barrier Reef since 2016, but the Southern Reef had dodged them all.  Not this time. We have visited Heron Island, The Keppels, Lady Musgrave, Lady Elliot, Fitzroy Reef and North West Island in the past.  All these locations are in the Southern Reef.  Water temperatures were recorded at a ridiculous 29 degrees in some places over this last summer. 

When corals are under stress, in this case, due to rising ocean temperatures, they expel their marine algae (known as zooxanthellae) that live in their tissues, revealing a bright white skeleton.  They are not dead, but they are then at risk of starvation and disease.  They can recover over time but only if the water temperature returns to normal. 

When I visited Lord Howe island in March this year, their reef too had been impacted by the same coral bleaching event.  It was obviously very recent as the white ‘blobs’ scattered randomly in every underwater vista were a very bright white. Over time these bright white coral skeletons get smothered by a murky brown algae growth. The coral may recover over time or die.

These are some photos I took at Lord Howe in March …

So it was with some reluctance but also eagerness, that I jumped in for a look myself (not to mention it was cold.) At first glance the fish life was the same and I didn’t see Lord Howe’s scattered white blotches. But it soon became apparent the corals were suffering. There were scattered bleached corals, some smothered in brown algae, others fighting it off and there were large areas of the murky brown algae suffocating areas of acropora coral.

This brain coral is a good example.  Brain coral is known as a robust coral, less reliant on their marine algae, but when their algae is expelled due to heat stress, the brain coral too loses its colour. These brain corals can live up to 900 years.  But not if we don’t protect our reef.

Rising ocean temperatures caused by climate change are the primary cause of coral bleaching.  This is happening to reef systems all over the world. Climate change is the biggest threat to our Great Barrier Reef. We surely all want to protect our wonderful reef for future generations.

On a positive note, the underwater life was still vibrant as ever. I found this small Magnificent Sea Anemone as soon as I jumped in. It was actually quite green so my photos haven’t quite captured its true colour.

As I snorkeled further on I was hoping to find another Magnificent Sea Anemone (I am a fan of these in case you haven’t realised), one I’d discovered in 2023. They don’t move and they can appear quite different in shape, size and colour depending on the outer structure’s retraction, so it’s fun to revisit these. It was a hot pink one. Coral bleaching impacts Anemones so I was a little concerned about how it was surviving. I’d almost given up, when I spotted it.  The Anemone was open so the hot pink outer structure was barely visible, only the tentacles. The tentacles were colourless and bleached white, as a result of the coral bleaching event. Do their resident Anemonefish suffer too? 

These resident Pink Skunk Anemonefish were quite active and far less shy than on my last visit.  In fact, I wasn’t able to snap a photo with any Anemonefish in those shots. This time I was, but from my reading, a bleached Sea Anemone reduces the fertility of the Anemonefish it is hosting, so they are impacted.

Last year’s photo …

This year’s photos …

It was a quick visit to Lady Musgrave so I only sampled a very small area of the lagoon. We will visit again in November when the turtles are active. After 4 weeks of glorious sunshine, the sun is no longer shining. We are now anchored in Pancake Creek while I’m writing this post, where we have flat water, sandbanks all around us and an endless amount of rain!

Remember, to see a larger view of the photos, simply click on each photo.