The evening before the summer solstice was, for hungry swifts, perfection. Warm, dry and calm conditions meant one thing – the insects were flying high, and the swifts were up after them. I stood underneath a group of six of them as they shot back and forth, wheezing their urgent call. Earlier in the day over Lough Ree, I had watched a white-tailed sea eagle glide in circles through pockets of warm air, and envied its seamless, relaxed, unhurried movements. But for a thrilling life – and that’s the one I go for – be a swift.
The next day, Grianstad an tSamhraidh, delivered cloudless skies and a view of the sun at its highest and most lingering, its solstice peak. I went straight for the sea and met a good friend in a small cove in Wicklow. The tide was out. We heard a howling, mournful sound from the water; a group of grey seals, some on their backs, others with their cone-shaped heads pointed in our direction, were loitering close by with no intention of giving ground. If they could talk, they’d have kept it short: “Ladies, not here, thanks”.
We took the hint. We clambered southwards over limpet and periwinkle-coated rocks to a small inlet nearby, and waded out through a fringe of dark, rubbery kelp that parted around our legs and slapped back into place behind us. All around us was dark brown oarweed, Laminaria digitata, anchored to the rocks by claw-like holdfasts, with its broad blade split into finger-like segments that gave it its Latin name. It’s one of Ireland’s most overlooked marine species.
Still on my feet, my toes fiercely gripping whatever uncovered spaces on the rocks I could find, with the glass-clear water just up to my thighs, I looked down. The sun was like a torch into the water, illuminating the swaying gold and amber seaweeds, among them the leathery cuvie, Laminaria hyperborea.
These are underwater kelp forests. The stipe of the cuvie is rough and brittle; bend it and it will snap. In deeper waters, beyond where the seals were standing guard, these seaweeds can rise up to three metres from the seabed towards the light. Cuvie offers sea creatures three places to live. The gnarly holdfast, anchored to the rocks, is home to hundreds of invertebrate species. Epiphytes accumulate on the stipe over the years, encrusting it with life. A 2021 study of western Irish kelp forests found 313 unique species – a diverse habitat that nearly all of us will never get to see in real life.
[ This killer pet has driven 73 species to extinction, and roams free in IrelandOpens in new window ]
Beneath us was seaweed older than the kids playing in the nearby cove. Some of the cuvie plants can live for up to 15 years, laying down annual growth rings that scientists can count to estimate their age, just like an oak tree in a wood. Their story stretches much further back. Research from the KelpRes project, an Environmental Protection Agency-funded project led by the University of Galway, examined cuvie populations across Ireland. The highest genetic diversity was found on the southern coast of Ireland, which may have been a refugium during past glaciations – a pocket of ice-free water where kelp survived at a time when much of Ireland lay under ice. This ancient gene pool has existed ever since. With ocean warming from climate change, cuvie – a cold-water species – is under pressure. In Spain and Portugal, it’s being replaced with golden kelp (Laminaria ochroleuca), a warmer-water species. It arrived in Irish waters in 2018 at Scotch Port in Belmullet, Mayo.
Kelp has always been valuable in one way or another. Long before we had to concern ourselves with ocean warming or biodiversity loss, people harvested it for something else entirely. Two hundred years ago, iodine was discovered in kelp, and by 1820, production had begun in Scotland and France to meet demand for medicine and early photography. Ireland followed. Harvesting, drying, and burning were done on the seashore, with the final purification taking place in factories inland, where the iodine was dried and packed into wooden kegs. Temporary stone structures were built every season along the shore, and some remain. Irish kelp was valuable because it was higher in iodine than its Scottish equivalent, and it was sent over to Glasgow – the centre of the kelp trade – to be processed.
[ Cornafulla Bog is a gold mine. Let’s not squander itOpens in new window ]
Back in the sea, under the baking solstice sun, we floated on our backs and watched two oystercatchers on the rocks, their orange bills popping in the light. Underneath, the oarweed waved in the water, stroking us. In 2023, a team from Queen’s University Belfast spent nearly two years on the exposed rocky shores of Donegal, measuring something nobody had properly looked at before: how much carbon the kelp produces and how much drifts away. They discovered that these wave-lashed stands of oarweed were producing more living material than deeper kelp forests elsewhere. In May, when daylight lengthens and the seawater warms up, the growth of oarweed surges, and fragments and fine particles break free, becoming food for creatures that can’t reach the shore. The kelp is like a supermarket for deeper-water species. These fragments also carry carbon into deeper water, and if enough of it sinks deep before it breaks down, it stays out of the atmosphere.
Floating in the water with my friend – underneath us, kelp growing, breaking, drifting away into the depths of the Irish Sea – it was, I thought, a perfect place to spend the longest day: above a watery forest, watched by seals, under the solstice sun.
