Mid-winter fabulousness — Norfolk Island's Reef

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.

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We’ve had the most fabulous mid-winter weather over the weekend here on Norfolk Island. With a full moon on 24 June, we experienced some wonderful low, low tides. Peak low tides always lag the full moon (and new moon) by a day or so. This time it left Emily Bay looking like someone had pulled out the plug!

But let’s get onto what has caught my eye over the last week. (By the way, you can click on any image and a larger version will pop up.)

We have a couple snubnose darts, Trachinotus blochii, who are regular visitors to Emily and Slaughter Bays. I saw them in Emily on 16 June. Then, on 22 June, I hopped in at Slaughter Bay and saw them again, but this time they were accompanied by the biggest daddy of them all. The water was a little murky, but I did manage to capture a couple of shots (in the slide show at the bottom of this page). I guess that bodes well for some bubba snubnoses then!

Genus Goniobranchus — Genus *Goniobranchus*

Another great find (and a new one for me) this week was a small nudibranch hiding out under a rock shelf in Emily. I popped an image of it up in iNaturalist (do check this website out if you are interested in citizen science and wildlife, generally) and someone IDd it for me as being from the genus Goniobranchus.

A rather pretty group of goatfish have been chilling in the shallows of Emily for a couple of months. We have a few different types of goatfish here, but I’d not seen these ones before. You can see the other goatfish species under that heading on the Reef Fish page of this site. I finally managed to get some decent images of these, too, and an ID. It turns out they are Francis' goatfish - Upeneus francisi. Common to all goatfish, these guys have barbels – a pair of whiskery ‘feelers’ (or a goatee, hence their name) – protruding from their chins. These are studded with taste buds and are used to probe the sand in order to detect their prey.

Francis' goatfish - Upeneus francisi

Australian goatfish - Upeneus australiae

Snubnose dart - Trachinotus blochii

Banded scalyfin versus a sea hare

Sea hare with his mate, the tiny elysia

The final noteworthy observations this week are of sea hares. They’ve been in hiding for a month or two, tucked under rocks in ones and twos. But this week there seemed to be more of them out and about; some were grazing, but I saw quite a few with their heads up as if sniffing or tasting the seawater (images in the slifeshow, above). I chanced upon one being attacked by an aatuti (commonly known as a banded scalyfin, Parma polylepis). The sea hare squirted ink repeatedly, which definitely confused the aatuti. This vivid purply-red dye is toxic and used to deter predators. And I think it worked! See the images in the slideshow, above.

Another sea hare, a white-speckled one, Aplysia argus, was hanging out with a teeny tiny blue-spotted elysia, Plakobranchidae, a miniature cousin. These two are the original ‘Odd Couple’! You can see these two in the slideshow (above). To give you some idea of the scale of things, I could fit the sea hare into the palm of my hand.

And to finish, I have a lovely image of another sea hare – an underwater Shrek – image below!

Isn’t nature grand?

White-speckled sea hare - Aplysia argus — White-speckled sea hare - *Aplysia argus*

September 13, 2026

No seagrass, but plenty of turtles

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.

September 6, 2026

Watching El Niño from Norfolk Island

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.

September 2, 2026

What the world’s reefs are telling Norfolk Island

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.

August 25, 2026

When the map changes

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.

August 24, 2026

Endemic, native, undescribed – what do these words actually mean?

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.

August 16, 2026

What’s grazing in the green stuff?

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?

August 8, 2026

The clam beneath Emily Bay

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.

August 1, 2026

Reflections of an accidental marine scientist

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.

July 24, 2026

From ridge to reef: unpicking the Waterway and Wetland Strategy

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 13, 2026

Reef reality in pictures

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