Wednesday 27 July 2022

Under the sea: exploring Skomer's marine life

For much of the spring and summer, Skomer is a hive of activity with over a million seabirds filling the cliffs and burrows, many of them busily raising chicks. The sights, smells and sounds of this breeding rush are hard to miss, from puffins diving into burrows with beaks full of sandeels to the cacophony of calls from the cliffside colonies. This abundance of life, however, is only the tip of the iceberg; equally impressive natural wonders reside beneath the waves.

Shanny © Becci Jewell

Blue jellyfish © Becci Jewell

Moon jellyfish © Becci Jewell

Dive in and take a moment to recover from the shock of the chilly Atlantic waters. Once your breath has slowed and your eyes adjusted, a multicoloured world awaits. Seaweeds in all shades of brown, red and green rise from the seabed, keeping time with the wash of the waves. Splotches of bright pink encrusting algae coat the rocks beside cushions of vibrant orange breadcrumb sponge and clusters of lemon-yellow dogwhelk eggs. A pulsating rainbow appears before you as a translucent comb jelly propels itself through the water, beating rows of combs scattering the light in all directions. On encountering a tasty morsel (friends and family included), this seemingly featureless creature yawns wide and engulfs their prey in a flash. Smaller and more spherical but equally as alien, sea gooseberries trail two long tentacles, fishing on the go. There’s life everywhere you look.

Comb jelly © Becci Jewell

The seas around Skomer are so rich in marine life they’ve been protected by a Marine Conservation Zone since 2014 and were recognised as a Marine Nature Reserve for 24 years before that. The incredible biodiversity here is due to the variety of habitats found around the island, the strong tidal flows, and the influence of warm and cold currents. Steep and exposed cliffs, wave-swept rocks and sheltered bays provide a multitude of homes for many different species, the strong tidal flows deliver food and nutrients, and oceanic currents bring warm-water species from the south and cold-water species from the north. You’ll find bright red multi-armed sunstars from the north living alongside scarlet and gold cup corals and yellow trumpet anemones from the south in a colourful cocktail of marine life.

Two metres tall and with broad brown blades, kelp is a giant among seaweeds. What’s more, it’s an ecosystem engineer creating habitat and boosting species richness by providing shelter, habitat and food for a whole host of marine species. In North Haven, spider crabs shelter amongst the kelp, clutching at the stipes or lumbering slowly across the seabed on their long, long legs. Wrasse briefly emerge from the kelp canopy whilst, if you have the patience to look for them, tiny blue-rayed limpets cling to the blades. These miniature limpets, with electric blue stripes on their fingernail-sized shells, graze the algal film found on kelp fronds. What’s more, kelp also absorbs and stores carbon dioxide, improves water quality and helps buffer the shoreline from stormy seas – a real champion of our oceans.

Photograph from above of a spider crab with very long legs
Spider crab © Becci Jewell 

Photograph of a blue-rayed limpet with three horizontal blue stripes along its body
Blue-rayed limpet © Becci Jewell

Green-brown kelp against blue water
Kelp forests © Becci Jewell

There’s more. North Haven is home to seagrass (also known as eelgrass), the only underwater species of flowering plant found in Britain, and it’s another ecosystem engineer. Its roots stabilise the sediment in which it grows, in turn improving water clarity. It provides food and shelter to many species, and it absorbs and sequesters carbon. Perhaps most importantly though, seagrass beds are important nursery grounds for a huge number of species including the juveniles of many commercially important species of fish. Seagrass is very rare in Wales and is now being actively restored all around the UK, including in nearby Dale. With such an impressive skillset, it’s little wonder.

Eelgrass © Becci Jewell

Eelgrass © Becci Jewell

Sea Gooseberry © Becci Jewell

Comb jelly © Becci Jewell

The range and breadth of marine species that inhabit and depend on the waters around Skomer is vast. From the tiny Cornish sucker fish sheltering beneath boulders as the tide retreats, to the much feared (but incredibly beautiful) jellyfish, the summer schools of mackerel, the seals that haul out on the beaches, and the squid-scarred Risso’s dolphins that visit the Sound. All play their part in the dynamic marine ecosystem, the very same ecosystem on which Skomer’s seabirds depend. Let’s show them some appreciation on our next visit to Skomer and keep doing all we can to save our seas.

Cornish sucker fish © Becci Jewell

Blue jellyfish © Becci Jewell

 - Becci Jewell, Skomer Volunteer 

Saturday 2 July 2022

Burrow walking and biscuit breaks: June on Skomer

Bull Hole, for those who don’t know it, is the largest colony of razorbills and guillemots on Skomer – a seething vertical seabird city that emanates waves of croaky cries and guano aromas – and counting the auks there was my very first task as Seabird Monitoring Volunteer.

With my unpacked bags and food for a month stacked at the farm, Ceris gave me a whistle-stop tour of auk counting as the daily 4pm deadline crept closer. She subdivided the cliff into sections and talked me through the boundaries with chat along the lines of “you see the crack in the cliff face that looks like a lightning bolt”. Once we were sure we were looking at the same area and were counting the same species, we were off with binoculars raised and thumbs poised at our clickers.

Click for every guillemot you see... © Becci Jewell

Guillemot © Becci Jewell

Next followed a period of eye-wateringly intense concentration as I stared at the mass of auks huddled on the ledges, heads bobbing and squabbles erupting. Were the birds standing three or four deep on that bit in the shade? Had I already counted the group on the ledge above, and were the birds on the lower ledge breeding there or just loafing? Now where had I got to on the main ledge? Finally, when I was as confident as I could be that I’d counted each and every individual and, crucially, had counted them only once, came the scary moment of revealing my final tally. Within 10% of Ceris’ count and all was well. Outside 10% of Ceris’ count and we were back to the beginning, counting again. This mix of beautiful setting, breath-taking wildlife and intense concentration tinged with fear set the scene fantastically for my month of seabird monitoring on Skomer.

Some of the seabird colonies can only be counted from the sea and if I thought counting seabirds from land was hard (which I did and still do), counting them from a boat was a whole new level of difficult. Even on fair-weather days, strong tides scour the island creating waves, swirls and eddies that jostle and spin the boat. Craning our necks up at the cliffs, keeping track of where we were counting just got much, much harder. Slowly but surely, we got there though, helped by a run of excellently timed good weather. As my dodgy tan lines and knowledge of ABBA lyrics grew, the list of sections left to count shrunk until, finally, the auk counts were done for another year.

Kelda, Eve & Becci 

As the good weather came to a rainy and blustery end, we started the Manx shearwater counts at the first of 18 plots around the island. There are approximately 700,000 Manx shearwaters on Skomer between March and September yet it’s entirely possible to visit the island without seeing any of these nocturnal birds. Breeding pairs lay a single egg usually in May, from which point one of the pair remains in the burrow to incubate it whilst the other bird forages in the productive waters of the Irish Sea.

Manx shearwater at sea © Becci Jewell

Manx shearwaters produce a garbled and quite spooky call, usually at night, but can also be tricked into calling during the day by the sound of another Manx shearwater. So, at each of the 18 plots, we gently crawled around on fragile burrowed ground, poking a small speaker into the entrance of every burrow and noting whether the recording prompted a reply from the bird on egg incubating duty. Going burrow to burrow, we crawled through dense bracken, tussled with stinging nettles and bum-shuffled down steep clifftop slopes in bright sunshine, pouring rain and everything in-between, clutching our speakers and clickers. Regular biscuit breaks were instrumental in maintaining morale and focus, particularly on the days when incessant rain crept into our hoods and seeped up our sleeves.

When the weather allowed, we switched to counting kittiwakes and fulmars around the island, again some from land and some from the boat. Instead of counting individuals (as we did for razorbills and guillemots), we counted nests (for the kittiwakes) and sites (for the fulmars). These counts were an epic whole-island effort as we set off in different directions to cover all sections of the island, ticking them off as the end of the four-week seabird counting window approached. Brilliant teamwork saw the kittiwake and fulmar counts done with a few days to spare and our efforts returned to the final four Manx shearwater plots which were finally completed by a tired team running on tea, cake and determination. With faces caked in wind-blasted soil, we checked the last burrows before handing in our clickers and gingerly tiptoeing back to more solid ground.

The last Manxie plot © Becci Jewell

A grubby but happy team!

The days were long, the weather unrelenting and the birds not always cooperative. Plus, I often couldn’t quite make out the crack in the cliff that looked like a lightning bolt. I’d not swap a day of it though, working with a great team of people on an island teeming with life. As well as learning how the seabird counts are carried out, I was lucky enough to join some of the researchers on the island and assist with the weighing of chicks and the ringing of adults, learning more about the seabirds that depend on Skomer and the surrounding seas. I’m extremely grateful for all the knowledge shared and memories accumulated. From the seabirds that fill the burrows and transform the cliffs, to the harbour porpoise that sweep by with the tide and the glow worms that illuminate the bracken, Skomer is a truly special place.

Becci with razorbill chick 

Glow worm © Becci Jewell

Sunrise from the Farm © Becci Jewell