Norfolk Island's endemics on record — 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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DAY 14 – MARCH FOCUS ON NORFOLK ISLAND’S REEF

It is fascinating to me that, in terms of studying our biodiversity, there is still a slight feel of the frontier to Norfolk Island. So remote and isolated from any other land mass, it stands to reason that we have some different species that are found only here, or within in a very limited geographical area (I am thinking of the Kermadecs to our east, which are just a little further south but with a similar climate).

Norfolk Island, and Phillip Island (our more immediate southerly neighbour) like the Kermadecs, are of volcanic origin. Isolated volcanic islands are noted as being ‘cradles of endemism, contributing substantially to global biodiversity’.[i]

It is worth noting the difference between endemism (where a species is only found in a single defined area) and species richness (the number of different species in a defined ecosystem), as these tend to be relevant when it comes to prioritising conservation efforts.[ii] ‘When compared to mainland areas, oceanic islands in general are known for their high percentage of endemic species but only moderate levels of species richness …’[iii]

And Norfolk Island is no different.

When I see something new when I am out on my swim, there’s always that question, is this a new species or subspecies I am seeing? I often wonder about some of our banded snake eels and whether there is an endemic subspecies among them. And, of course, our corals. As I have mentioned before in these pages, coral researcher Professor Andrew Baird believes up to 30 per cent of our coral species are as yet undescribed, and some of these may be endemic.

How exciting is that?

One endemic species found in our marine habitat is the Norfolk Island blenny, Parablennius serratolineatus, which I’ve often spotted sheltering among the spines of sea urchins. They are easily recognisable, at about 10 to 13 mm in length, with a broad dark stripe and some faint brown spots on their head. This blenny is a shy guy, who tends to hang out at the pier end of Slaughter Bay and in Cemetery. You’ll see them elsewhere, of course, but those are the places where they are most likely to hang out.

However, judging by my photographic record, and a hunch, I am not seeing them as often as I used to. Because of this, I have asked other snorkellers to let me know where and when they see them.

Because this species is so localised, they are vulnerable to habitat degradation and possible effects of climate change; consequently, they are listed as vulnerable on the IUCN’s Red List.

References

[i] Geodiversity and biodiversity on a volcanic island: the role of scattered phonolites for plant diversity and performance, David Kienle, Anna Walentowitz, Leyla Sungur, Alessandro Chiarucci, Severin D. H. Irl, Anke Jentsch, Ole R. Vetaas, Richard Field, and Carl Beierkuhnlein.

[ii] A global assessment of endemism and species richness across island and mainland regions, Gerold Kier, Holger Kreft, Tien Ming Lee, Walter Jetz, Pierre L Ibisch, Jens Mutke and Wilhelm Barthlott.

[iii] ibid

October 28, 2026

When storms rearrange the reef

Sometimes the sea rearranges a reef in a matter of hours! In the third article of my six-part photographic series, I revisit corals broken, overturned or swept away by powerful swells and storm surges. Some disappeared altogether, while others found surprising ways to survive. Five photographic sequences reveal just how dramatically Norfolk Island's reef can change.

October 26, 2026

When the reef fights back – coral growth and recovery

Not every coral story ends badly! Among six years of underwater photographs are some wonderful examples of growth, survival and recovery. From corals that have grown spectacularly to others that have survived bleaching, breakage or even being turned upside down, this second article in my photographic series celebrates some of the reef's more encouraging stories.

October 24, 2026

The neighbours – six years of watching the same reef

When I began photographing Norfolk Island's reef in 2020, I simply recorded whatever caught my eye. Six years later, those photographs have become a record of individual corals and their changing fortunes – growth, competition, survival and loss. This is the first of six articles looking back at what I've seen, and sometimes what I wish I hadn't.

October 10, 2026

Pulling the rugosity from out of the reef

What do ‘rugosity’, structural complexity and channeling your inner fish have in common? Quite a lot, as it turns out. This week I’m looking at how all the lumps, bumps, branches, holes and ledges on a reef create habitat – with a brief detour into one of my long-standing tricks for navigating tertiary study: write down the jargon until it starts to make sense.

September 27, 2026

How does a sea slug smell?

It started with a close-up of a little Elysia and two rhinophores that looked like tiny rolled-up scrolls. Once I noticed them, I started going back through years of sea-slug photos and realised just how wildly different these sensory organs can be – ridged, rolled, curled, tubular and, in sea hares, distinctly rabbit-eared. So this week’s rabbit hole is all about how sea slugs ‘smell’ underwater, and why their noses come in so many different shapes.

September 19, 2026

The Elite Fleet sails in

Nearly six years ago, my very first blog post was about the strange blue and violet creatures that live at the ocean’s surface – a group I christened Norfolk Island’s ‘Elite Fleet’. Since then I’ve seen plenty of bluebottles and the occasional violet sea snail, but never a by-the-wind sailor. Until this morning. Velella velella is not a true jellyfish, but a colonial hydrozoan with a transparent sail that lets the wind help carry it across the ocean. So what exactly is this extraordinary little creature, how does it ‘sail’, and what connects it to the rest of the fleet?

September 18, 2026

In a nutshell – where I stand on the proposed Norfolk Island Marine Park

I support the proposed expansion of Norfolk Marine Park and its renaming as Norfolk Island Marine Park. There is much to welcome – strong offshore protection, no mining, and recognition of the importance of sustainable local fishing. But I also have some reservations. Why does Cascade need to be removed from the Marine Park at all? How will more than 430,000 km² actually be monitored and enforced? How do we make sure Norfolk people have a genuine role in management? And, above all, how do we ensure that the enormous new park does not draw attention away from the small, stressed reef immediately beside us?

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.