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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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Norfolk’s water quality – when action is reported as outcome
June 15, 2026
Norfolk’s water quality – when action is reported as outcome
June 15, 2026

A recent Australian Government media release presents investment, monitoring and catchment works as progress on Norfolk Island’s water quality. Some of that work is useful, and some of it was badly needed. But activity is not the same as proven improvement. This post looks at Kingston sewerage, wetlands, cattle, acid sulfate soils, groundwater and reef health, and asks whether Emily Bay and Slaughter Bay are actually being better protected.

June 15, 2026
How surgeonfishes got their name
June 14, 2026
How surgeonfishes got their name
June 14, 2026

Surgeonfish are named for the sharp little scalpels near their tails, but on Norfolk’s reef their more useful work happens at the other end. Pencil surgeonfish, bluespine unicornfish and their relatives help browse algae across the reef – a small daily job that becomes very valuable on an algae-rich lagoon reef like ours.

June 14, 2026
A shrimp storm
May 28, 2026
A shrimp storm
May 28, 2026

While setting my research cams last week, I swam into what looked like an underwater snowstorm. It appeared to be the aftermath of a mass moulting event, with large numbers of tiny, translucent shrimp-like exoskeletons drifting together near the surface.

May 28, 2026
Kingston dredging: what happens when a reef does not fit the framework
May 28, 2026
Kingston dredging: what happens when a reef does not fit the framework
May 28, 2026

This correspondence with DCCEEW is about more than one dredging proposal. It is about what happens when an ecologically distinctive place is assessed through standard tools that do not always make its most important values easy to see. I am publishing it here because that is something we need to be aware of, both on Norfolk Island and more broadly in Australia.

May 28, 2026
Kingston dredging: the project advances, the questions remain
May 24, 2026
Kingston dredging: the project advances, the questions remain
May 24, 2026

Kingston dredging is edging closer, and the paper trail is growing. This post brings together earlier correspondence with the Department and the latest media release so readers can see what has been asked, what has been answered, and what still remains unclear about the project, its rationale, and the protections proposed for the reef.

May 24, 2026
The lime-green coral in Slaughter Bay – a 40-year paper trail
May 17, 2026
The lime-green coral in Slaughter Bay – a 40-year paper trail
May 17, 2026

Green Mountain – the name I give this coral in my database – is a coral I’ve photographed for years as I swim past. Then I found its backstory in the Norfolk Island National Parks archives: a rough map, reused paper, a note in the margin – ‘still thriving’. That’s how baselines begin.

May 17, 2026
What Norfolk Island’s reef tells us about environmental blind spots
April 5, 2026
What Norfolk Island’s reef tells us about environmental blind spots
April 5, 2026

The Kingston dredging proposal on Norfolk Island raises a bigger question than dredging alone: how well do standard environmental assessment tools capture the real significance of a remote and unusual reef system like Norfolk Island’s?

April 5, 2026
Hammer coral time!
March 30, 2026
Hammer coral time!
March 30, 2026

Hammer corals have unique tentacles that are large, fleshy, and tubular; these terminate in a ‘T’-shaped, hammer-head or anchor. Beneath all these softly waving tentacles is an extraordinary skeleton structure, which helps define them as a large polyp stony coral.

March 30, 2026
Norfolk Island’s fishes: drifters, residents and the ones still missing
March 24, 2026
Norfolk Island’s fishes: drifters, residents and the ones still missing
March 24, 2026

Norfolk Island’s fish fauna reflects both connection and isolation. Some species may arrive from elsewhere as drifting larvae, some populations appear to persist locally, and some fishes known from islands on either side of Norfolk have still not been recorded here. This post looks at what old survey work, regional checklists and genetic studies suggest about that more complicated picture.

March 24, 2026
18 Jun 2025 (20)_crop.jpg
March 7, 2026
Alveopora or flowerpot coral – how to tell the difference
March 7, 2026

They look alike at first glance, but Alveopora and flowerpot corals are not the same. The easiest way to tell them apart is to count the tentacles.

March 7, 2026

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