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.

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

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*

Jul 28, 2025

Reef relief

Today, 28 July, is World Nature Conservation Day. After the dry 2024, Norfolk Island’s reef is looking healthier – a brief reprieve as less water - laden with nutrients - flowed into the lagoon. These photos show what’s possible. It’s a reminder that recovery is within reach – though renewed runoff could quickly undo the gains.

Jul 20, 2025

Emily Bay's big 'brain' coral

In Emily Bay, Norfolk Island, a single coral bommie – Paragoniastrea australensis – has stood for decades as a micro-reef, harbouring diverse marine life and local memories. Once photographed in 1988 and still thriving today, it remains a keystone of reef biodiversity and a living link between past and present.

Jul 14, 2025

Biodiversity matters

Over five and a half years of snorkelling Norfolk’s lagoon, we’ve documented 23 fish species not previously recorded in this area. Some are local ghosts, others climate migrants. These observations help us understand and protect what makes our reef so special.

Jun 17, 2025

Poop power

Not all poop on a reef is bad poop. In fact some kinds of poop can be a reef’s most important invisible engine. Fish poop, bird poop – even poop that gets eaten again by other fish – all of it keeps the ecosystem ticking over in a way that’s nothing short of extraordinary.

Jun 13, 2025

Glimpses of recovery: what the reef could be if we let it

Day 6 of this photo series from Norfolk Island coincides with the final day of the UN Ocean Conference in Nice. After a week of documenting decline, today’s post offers a different view – what reef recovery can look like when conditions improve. Drought in 2024 gave the reef a break, and the results were unmistakable: healthier corals, lower disease, and more fish. This is what’s possible if we act.

Jun 12, 2025

Warning signs: quiet and unnoticed collapse of two coral colonies

Day 5 of my blog series for the UN Ocean Conference: two long-lived coral colonies in Norfolk’s lagoon died quietly from disease. No drama – just slow collapse and overgrowth by algae. A reminder that not all reef losses are loud, but they are happening.

Jun 11, 2025

Warning signs: what Norfolk Island’s reef is telling us

Day 4 of a week-long photo series from Norfolk Island, shared during the UN Ocean Conference in Nice. Today’s post spotlights a Hydnophora pilosa colony where white syndrome appeared suddenly and spread quickly, taking out around a quarter of the coral. In the months that followed, algae quietly filled the gap – a subtle but telling shift from coral to algae that’s happening across the reef.

Jun 10, 2025

Warning signs: coral disease takes hold

In Day 3 of this blog post series, published while leaders gather at the UN Ocean Conference in Nice, we see Norfolk Island’s coral reef lagoon quietly delivering a stark warning: recurrent land-based pollution, coral disease, and delayed decisions are dismantling this ecosystem in real time.

Jun 9, 2025

Warning signs: coral growth anomalies – the slow cancers of the reef

Day 2’s post coinciding with the UN Ocean Conference looks at coral growth anomalies – sometimes called coral ‘cancers’. These slow-moving diseases quietly weaken coral colonies, making them far more vulnerable to storm damage and algal takeover. On Norfolk Island’s reef, I’ve watched this exact process play out over several years. This is how chronic stress silently dismantles coral ecosystems.

Jun 8, 2025

Warning signs: shifting baselines on Norfolk Island’s reef

Today is World Ocean Day — a timely moment to launch my week-long blog series on Norfolk Island’s reef. Each day this week, I’ll be sharing photo essays that document the slow but steady pressures reshaping this fragile reef. Today: how shifting baselines make us blind to what we’ve already lost.