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Norfolk Island's Reef

Discover a fragile paradise – Norfolk Island's beaches, lagoons and coral reef
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Out on A Swim

‘Out on a swim’ is a coral reef blog that tells the stories of the characters who live under the waves and what has caught my eye when ‘out on a swim’ in the lagoons of Norfolk Island. It is also a record of the difficulties Norfolk Island’s reef faces, like many others around the world, as a result of the poor water quality that has been allowed to flow onto it.

This page shows the most recent blog posts. For the complete catalogue, visit the ‘Out on a swim index’ page.

This blog is rated in the Top 20 Coral Reef Blogs in the world.

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Full moon rising over our home on Norfolk Island, #DownArthurs

Full moon rising over our home on Norfolk Island, #DownArthurs

September full moon on Norfolk Island

September 21, 2021

More changeable weather this week with poor visibility in the bays curtailing some of my observations, but the full moon last night brought us some beautiful, settled weather, right on cue, which meant I was able to get out into Slaughter Bay for the first time in ages.

What greeted me wasn’t too pretty either. There is one area of coral I have been watching since the marine researchers from the Sydney Institute of Marine Science were here in March and alerted me to the onset of white syndrome, or white band disease. I have kept an eye on it since then and watched as the colony has gradually died. This week it was virtually unrecognisable, covered by a thick growth of algae. You can see the progression of the disease, below. Heartbreaking.

View fullsize 4 May 2021
4 May 2021
View fullsize 11 June 2021
11 June 2021
View fullsize 20 September 2021
20 September 2021

A sure sign that things are warming up in the water was the sighting of a couple of Lady Musgrave blennies, Cirripectes chelomatus, out and about for the first time in yonks. I have seen them over winter, but it has been incredibly fleeting as they dashed for cover. This week my regular guy was happy to sit and be photographed. No sign of the chestnut eyelash blennies, Cirripectes castaneus, yet, though.

From now on, I expect to see these cheeky guys more and more. They tend to sit up on a prominent piece of coral, flutter up and then dive quickly back down and hide. And they will start to change colour as the season progresses to a beautiful greeny yellow with their blue tails. The first two images are from today. The others are to show you what I expect them to look like very soon.

View fullsize  Lady Musgrave blenny - Cirripectes chelomatus 20.09.21
Lady Musgrave blenny - Cirripectes chelomatus 20.09.21
View fullsize 17 November 2020
17 November 2020
View fullsize 2 February 2021
2 February 2021

Another fun photograph was of (I think*) a redcap triplefin, Enneapterygius rufopileus. These guys are a master of disguise. Probably less than 1 cm in length, they can be really hard to spot. Blink and they’re gone. The other image is of (I think*) a Doug’s eviota, Eviota hoesei. Similar in size to the redcap triplefin, and looking like a diminutive jewel, he has a black spot near his tail.

View fullsize Redcap triplefin - Enneapterygius rufopileus
Redcap triplefin - Enneapterygius rufopileus
View fullsize Doug's eviota - Eviota hoesei
Doug's eviota - Eviota hoesei

To round off the week out on a swim, I thought I’d post one of my favourite butterflyfish, the vagabond butterflyfish, Chaetodon vagabundus. This is one of a pair that were happily flitting around in Slaughter Bay yesterday.

Vagabond butterflyfish - Chaetodon vagabundus

Vagabond butterflyfish - Chaetodon vagabundus

When I first started observing and photographing, I had no idea that there were so many variations on yellow, black and white among the butterflyfish. If you hop over to my reef fish page and scroll down to the Butterflyfish heading you will see what I mean.

*I've tried to get a definitive ID on these tiny critters on iNaturalist.org, but so far I've been unsuccessful.

Tags Coral disease, corals, coral reef, Lady Musgrave blenny
← Turtles and snake eelsJockeying for space on the reef →
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No seagrass, but plenty of turtles
September 13, 2026
No seagrass, but plenty of turtles
September 13, 2026

Norfolk Island does not have seagrass, although one of our most conspicuous green algae is often mistaken for it. Feather and grape Caulerpa can both form striking patches across the lagoon. I take a closer look at what Caulerpa actually is, why it is so easily confused with seagrass, and where our green turtles fit into the story.

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September 13, 2026
Watching El Niño from Norfolk Island
September 6, 2026
Watching El Niño from Norfolk Island
September 6, 2026

El Niño is strengthening across the Pacific, but that does not tell us exactly what the coming months will bring to Norfolk Island. After a long wet spell, I am watching our rainfall and water supplies more closely again – and, underwater, keeping an eye on sea temperature, algae, coral recruits and the fish that turn up on the reef.

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September 6, 2026
What the world’s reefs are telling Norfolk Island
September 2, 2026
What the world’s reefs are telling Norfolk Island
September 2, 2026

Two major new coral reef reports carry a clear message for Norfolk Island: reefs can recover when pressures ease, but the time available for recovery is shrinking. Norfolk Islanders were raising concerns about water quality, runoff and the health of Emily and Slaughter Bays nearly forty years ago. Today we have much better science, a changing climate and a far clearer understanding of how closely the catchment and reef are connected. This article looks at what that means for water quality, long-term monitoring, dredging and how we manage Kingston from land to sea.

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September 2, 2026
When the map changes
August 25, 2026
When the map changes
August 25, 2026

A fish once thought to belong only to Norfolk turns up elsewhere; another appears here hundreds of kilometres beyond its known range. Cardinalfishes and a Sabre squirrelfish show how our maps of species distributions are revised.

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August 25, 2026
Endemic, native, undescribed – what do these words actually mean?
August 24, 2026
Endemic, native, undescribed – what do these words actually mean?
August 24, 2026

A Norfolk chromis that turned out not to be Chromis fumea, a blenny found nowhere else, and a tiny goby that may not yet have a name. A look at what we mean by native, endemic, undescribed and newly described – and why scientific names sometimes change.

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August 24, 2026
What’s grazing in the green stuff?
August 16, 2026
What’s grazing in the green stuff?
August 16, 2026

A proliferation of Bryopsis on the reef has brought some beautiful little underwater grazers with it. I follow the trail from sap-sucking sea slugs and egg masses to a bigger question – why is there so much Bryopsis around at the moment?

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August 16, 2026
The clam beneath Emily Bay
August 8, 2026
The clam beneath Emily Bay
August 8, 2026

I’ve seen the beautiful shells of Laciolina chloroleuca in Emily Bay for decades, but I’d never really stopped to wonder where the living animals were. It turns out they may be buried half a metre beneath the sand. A closer look at an easily overlooked clam, its extraordinary shell markings, and the hidden life beneath our lagoon.

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August 8, 2026
Reflections of an accidental marine scientist
August 1, 2026
Reflections of an accidental marine scientist
August 1, 2026

What I thought would be a steady plod towards retirement, with plenty of time spent nursing grandchildren, was abruptly upended exactly six years ago today. This is the story of how an environmental catastrophe changed the course of my life – and led me to reinvent myself. It is a reflection on how, and why, I became an accidental marine scientist.

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August 1, 2026
From ridge to reef: unpicking the Waterway and Wetland Strategy
July 24, 2026
From ridge to reef: unpicking the Waterway and Wetland Strategy
July 24, 2026

Norfolk Island’s draft Waterway and Wetland Strategy will guide work for the next ten years. I support its intent, but it needs to be clear, practical and measurable – joining the dots from ridge to reef so we know whether public money is improving water quality and helping the reef.

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July 24, 2026
Reef reality in pictures
July 13, 2026
Reef reality in pictures
July 13, 2026

Let the pictures do the talking. This is the reality on Norfolk Island’s reef today, laid out in a two-minute video.

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July 13, 2026

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