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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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The Emily Bay’s massive ‘brain’ coral, Paragoniastrea australensis, photographed on 6 July 2024

While you were sleeping ...

July 10, 2024

This post is a quick pictorial essay of one of our most recognisable coral bommies. This massive and incredibly slow-growing Paragoniastrea australensis sits off the Salt House inside Emily Bay on Norfolk Island. I have been told that it is a lot smaller than it used to be after sections tumbled off when storms came through. It’s still impressive, though, with many fish congregating around and within its folds. Sea anemones nestle in crevices, moray eels can sometimes be found poking out of holes, and banded scalyfins create their gardens on its sides. For some species, like the little peacock damselfish, Pomacentrus pavo, this coral is their world.

Most of the time, during daylight hours anyway, the unique maze across its face is a clear, crisply defined series of ridges. While all looks reasonably calm during the day, at night, while you are sleeping, the surface of the coral colony seethes with millions of tiny tentacles busily reaching out to find food, while others aggressively ward off opportunistic interlopers.

If you swim past just before dawn, as I did today, they will still be out, and you might notice that the surface of the colony has taken on a soft, fuzzy appearance. They also reach out with even longer ‘sweeper’ tentacles to ward off other corals that may want to invade, or grow, into their territory.

Below, you can see the coral during the day and in the pre-dawn. Click on each image to see a larger version.

I’ve posted about this species of coral before, so if you want to find out more, go here, War of the coral worlds! and, here, One hundred year-old coral gone in less that one hundred days.

View fullsize At night the tentacles come out
At night the tentacles come out
View fullsize They give the coral a velvety appearance
They give the coral a velvety appearance
View fullsize Longer sweeper tentacles also appear
Longer sweeper tentacles also appear
View fullsize Aggressively asserting their territory
Aggressively asserting their territory
View fullsize During the day the tentacles are retracted
During the day the tentacles are retracted
View fullsize A surge wrasse, Thalassoma purpureum
A surge wrasse, Thalassoma purpureum

The peacock damselfish, Pomacentrus pavo, that calls this bommie home

In Corals Tags corals, coral reef, bommie, Emily Bay, Norfolk Island
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Featured
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.

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.

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.

July 13, 2026
The red seaweed behind low-methane beef
June 28, 2026
The red seaweed behind low-methane beef
June 28, 2026

A small red seaweed on Norfolk’s reef has become part of a much bigger story. Asparagopsis taxiformis can look like a delicate red feather duster or, at another stage of its life cycle, like a tiny cottony pom-pom. It is beautiful, easily overlooked, and now being used in the cattle industry to help reduce methane emissions. This post looks at the reef oddity behind the low-methane beef story – and why repeated local observation can be more useful than it first appears.

June 28, 2026
From coral scar to aatuti farm
June 20, 2026
From coral scar to aatuti farm
June 20, 2026

Aatuti are bold little algae farmers, but how does one of their farms begin? Over the past year, I have been following several coral patches as small white scars became algal footholds, then larger defended patches. I still cannot say what caused the first wounds, but the photo sequences show something fascinating: on a reef where algae is already gaining ground, even tiny changes on the coral surface can become part of a much bigger story.

June 20, 2026
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

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