‘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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Slaughter Bay, Norfolk Island
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?
Read MoreHammer corals, Norfolk Island
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.
Read MoreJames Stuart’s three-striped butterflyfish, Chaetodon tricinctus. Image courtesy of the Mitchell Library, State Library of New South Wales; PXD 134
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.
Read MoreA juvenile flowerpot coral (Goniopora)
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.
Read MoreFlooding on the Kingston Common, Norfolk Island, 5 November 2020
We now have the 2025 Norfolk Island reef health report, so I’m taking the opportunity to translate it into plain English here. Sadly, it’s more of the same story in Emily and Slaughter Bays – a reef that can cope with some stress, but is being asked to cope with too much, too often.
Read MoreHalimeda with a bright green segment at/near dawn – chloroplasts concentrated in the new growth
Halimeda is a calcareous green reef alga that forms new segments overnight, shifts from white to bright green by dawn, then pales again as calcification begins. A quick look at one of the reef’s smartest algae.
Read MoreA bubble-tip anemone claims its real estate
Reef space is finite, and nothing ‘shares’ it politely. This short photo essay follows one bubble-tip anemone on Norfolk Island’s lagoonal reef as it holds a crater surrounded by Montipora. The coral builds a rim; the anemone holds the centre. Six years apart, and the argument continues.
Read MoreQuality Row, Kingston, Norfolk Island, January 2025. The year began deep in drought.
Norfolk Island’s reef in 2025 – a year in review. From NOAA bleaching alerts and the UN Ocean Conference ‘Warning Signs’ series to post-drought coral recovery and a wet winter revealed in long-term rainfall records, this post captures the wins, losses, and shifting baselines beneath the lagoon. Includes reef photos, highlights from Reef Relief, and standout stories from 2025 – from coral health and disease to boxfish biomimicry, sea urchins, nudibranchs, and heat-stress signals in anemones.
Read MoreForeshore vegetation and historic structures at Kingston and Arthur’s Vale Historic Area abut Slaughter and Emily Bays.
Herbicide use near Emily, Slaughter and Cemetery Bays raises questions about inshore reef health, heritage land management, and environmental protection on Norfolk Island.
Read MoreI took these photographs this morning, Monday, 8 December 2025. A few warm days of settled weather, little cloud cover and low tides in the hottest part of the day have led to some early bleaching on our reef. Bleaching doesn’t always mean death for our corals, but it is concerning to have this so early in the summer season. Fingers crossed the conditions don’t last and the reef can recover.
Read MoreThe flowerpot coral, Genus Goniopora, Norfolk Island, which I thought was a sea anemone (below)!
This is a thank-you note. Five years after my first Out on a swim post – written with zero marine science quals and a head full of questions – I’m still in the water, now as a PhD candidate, because an extraordinary mix of locals, volunteers, researchers and public servants decided to share what they knew. This is the story of how nature – and a very patient community – became my teachers.
Read MoreAerial image of Kingston Pier and the west end of Slaughter Bay, Norfolk Island. This map includes data from Airbus Imagery from the dates:20/06/2023–12/09/2023.
From Miami to Fiji, from Dubai to tiny village harbours on atolls, dredging near coral reefs has left a long trail of scars – even on ‘small’ projects. This follow-up to last week’s Kingston post walks through real examples of what happened elsewhere, and what that should make us think about before we dig up our own reef.
Read MoreA view to the west of the historic Kingston Pier, which directly adjoins the coral reef lagoon system of Emily and Slaughter Bays. The dredge site is on its east and southern sides.
How much risk are we really taking with the planned dredging at Kingston Pier – and how much protection do our corals actually have on paper? This piece walks through what the federal approval does and doesn’t guarantee, explains why sediment and light matter so much to the reef, and asks the hard questions we need answered before we trade a deeper channel for a shallower future.
Read MoreFigure 1: A clear lagoon and thriving corals – this is what the reef looks like when the water runs clean and the balance holds steady, taken on 6 November 2025, out where the tide and currents flush away the nutrients and any diseases. See the map below for where this one was taken (1).
After the long dry spell, the lagoon was crystal clear and full of life. But with the return of the rains, something else has returned too – the brown, filamentous mats of Lyngbya. It’s not seaweed, it’s a cyanobacterium, and when it takes hold it smothers coral and rubble alike. The reef’s way of showing us that every drop of water, from tank to tide, is connected.
Read MoreLong-spined sea urchin, Diadema savignyi, Norfolk Island
Ever seen a sea urchin that seems to glow blue from the shadows? That’s Diadema savignyi showing off its reef shimmer. Beautiful, a little spiky, and definitely not to be messed with.
Read MoreHalgerda willeyi, Norfolk Island
If ever a sea slug was channeling the 1970s, it’s Halgerda willeyi. With its groovy orange lines and chocolate-brown bumps, it looks straight out of a vintage lounge suite – the kind with shag pile carpet and bold floral cushions. Proof that nature was nailing retro design long before humans caught on.
Read MoreHaddon’s anemone, Emily Bay, Norfolk Island, 24 June 2024
This Haddon’s anemone has been quietly living in the middle of Norfolk Island’s Emily Bay for years, bleaching and recovering with the seasons. Like corals, sea anemones host microscopic algae that provide most of their food. When stressed by heat or rainfall changes, they lose colour – and tell a story about seasonal changes to the weather.
Read MoreMy school’s logo and motto, Christ me spede
I left school in the UK nearly 50 years ago, so it was a pleasant surprise to be invited to share some images and take part in an interview for an article about my work, to be published in the annual glossy magazine the school now produces. Here is the end product.
Read MoreEclipse butterflyfish – Chaetodon bennetti, Norfolk Island
September is Biodiversity Month – the perfect time to celebrate the astonishing variety of life on Norfolk Island’s reef. From new fish sightings to coral mosaics, every observation is a reminder of how much there is still to learn and protect.
Read more about why biodiversity matters, globally and right here in our lagoon.
Read MoreThis patch of Acropora is close to the colony discussed in this blog post, and is similar to how it would have once looked before disease took hold in that area..
I’ve tracked one plating Acropora coral from 2021 to 2025. In just a few weeks, white syndrome wiped it out. Nearly four years years on, it’s still smothered in algae and sea squirts, with only the tiniest hint of new growth. It’s a stark reminder: without tackling the root cause, we’re just watching the same sad story repeat itself.
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