Hidden beauties of our North Sea
May 2008
IN THE GEOS: Oaten pipe hydroids, Tubularia indivisa, in the geos at Duncansby Head. [photo: George Brown]
by Marion Perutz
All around the country, volunteer scuba divers are carrying out surveys to record this life through a Marine Conservation Society coordinated project, ‘Seasearch’. Seasearch is a nationwide initiative to collect information on the shallow, near shore habitats and species all around the British coastline. This data is collated and used to improve conservation of our coastlines. By mapping habitat and distributions of species we are able to identify particularly rare species or sites in need of protection.
The near-shore stretch of coastline in the North-East of Scotland was until recently one of the least surveyed areas in the country and possibly for good reason. Setting out to dive in such unpredictable and often ferocious waters as the North Sea is a challenge. Even when sea conditions are good, poor visibility may render diving unsuitable. However, Seasearch divers have been braving these conditions, armed with slate and pencil, to make records of the seabed and the habitats and species it supports.
As a regional Seasearch coordinator, people often ask me what there is to see under water, to which my response is never short. The North-East has an immensely diverse coastline from exposed rocky reef to sheltered bays, from bare sand to lush kelp forest. Even ancient ship wrecks are teaming with life. Seasearch started its work here in 2004, since when volunteer divers have surveyed over 100 sites of many hundreds of species between Duncansby Head in the north and Dunnottar Castle, south of Aberdeen.
The jagged, vertical cliff line seen at many sites in the North-East often continues beneath the waves and creates a particularly rich diverse known as a rocky reef. In the far northeast corner of Scotland the towering cliffs at Duncansby Head reach 64 metres in height and are characterised by steep-sided inlets locally known as geos. The layered mudstone provides an ideal nesting site for thousands of seabirds and the cliffs resound with the calls of guillemots, razorbills, gannets and kittiwakes, which fill every available space, an amazing sight – if you are not overwhelmed by the smell of guano.
Underwater the geos give way to huge sheltered but lightless caverns, where amazingly, certain species thrive in the extreme movement of tide and wave. We found the walls of these caverns to be covered in a lacy white sponge and the bright red bulbous baked-bean seasquirt with dark green bryozoans – sea mats and mosses – protruding from the wall like over-sized pipe cleaners. By the entrance to the geo, the light shone though a meadow of oaten pipe hydroids like daisies glinting in the sun. Swimming out of the geos on to the seaward-facing walls, we found dense patches of fluorescent pink-and-yellow jewel anemones and huge, grey, leathery elephant’s hide sponge.
Searching in the rock crevices and between boulders revealed an abundance of crustacean life – crabs and lobsters – including the spiny lobster or crayfish Palinurus elephas, poking its enormously long antennae out from under a boulder. This species is normally found on the west coast but Seasearchers have recorded it in the Moray Firth, the first finding on the whole of the east coast of Britain. Highly prized to eat, this creature has been heavily exploited and is now listed as a Biodiversity Action Plan species to give it extra protection.
Another fearless inhabitant of these narrow cracks is the conger eel, a two-metre, powerful snake-like giant and a ferocious predator, although luckily for us its fury is usually taken out on smaller prey than divers.
In the outer Moray Firth in north Aberdeenshire are the towering cliffs of Troup Head, famous as mainland Scotland’s only gannet colony. Here the cliffs give way to steep walls surrounded by a maze of gullies and caverns. The bedrock is blanketed with a thick covering of soft, pale coral, the aptly-named dead men’s fingers. Amongst the coral, and easily seen by divers, are many other animals and seaweeds.
In exposed areas plumose anemones thrive, standing like a cauliflower, firmly attached to the rock. Lightbulb seasquirts, each a gelatinous box with a bright white stripe, can illuminate an entire wall. Seaslugs are common inhabitants of such communities – some immensely colourful, while others are perfectly camouflaged. Many are highly specialised to a food animal around which they live, such as the dead men’s fingers. Their eggs are often seen before the parent, laid in a beautiful spiral mass.
In the shelter of a crevice, the red-eyed velvet swimming crab can often be seen, standing on its hind appendages, pincers erect ready to defend its space from intruding divers. The cuckoo wrasse, one of the more colourful members of the rocky reef community, often shares its shelter with crustaceans. Cuckoo wrasse start life in a harem of red females guarded by one iridescent blue-and-red male. When this male leaves, another female takes his role and becomes a male.
Often found on rocky reefs are kelp forests, the rich forests of the sea. Kelp is usually found at depths between the intertidal zone and 20 metres, given sufficient light. Tens of species exist on the kelp plant. On the holdfast, attached firmly to the rock, are sponges and seasquirts. Spider crabs hang on to the stipes, or stalks, often camouflaged by the tangled mass of algae they decorate themselves with, in contrast to the painted topshell, with its bright red-and-blue stripes. On the fronds of kelp are bryozoans, such as the seamat and iridescent blue-rayed limpets.
In the spring one of our most oddly shaped fishes, the lumpsucker, rises from the depths to spawn in the kelp forests. After laying, the female disappears back to the deep, leaving the male to defend and aerate his clump of eggs – often found on a frond of a kelp plant – giving rise to the lumpsucker’s other common name, ‘sea hen’.
The many wrecks of the Moray Firth are a magnet for marine life. Often it is not possible to see the wreck but for the shoals of fish surrounding it and the carpet of animal fauna attached to the surface. Shallower wrecks, such as the MFV Pheron and the Fylla lying in the Moray Firth, are swarming with juvenile cod and poor cod. The red-and-white striped bibs often like to shelter under the flanks of the wreck and the cracks are used as shelter by fish such as ling, a long fish in the cod family with a beard-like barbel.
On deeper wrecks, such as the Remuera lying at 60 metres, we found large colonies of a bright white coral-like worm, aptly named the coral worm. These colonies form an important habitat for the tiny pea crabs, scale worms and shrimps, not to mention the bright red and extensively-armoured stone crab Lithodes maja, another new find in the North-East. Wrecks such as this one are important refuges for many species, being largely undisturbed by trawling.
People who have been diving in the region for 20 or more years say, “Seasearch gives our diving a new sense of purpose as well as the opportunity to be involved in practical marine conservation. It’s also great fun!”
Luckily you do not have to dive to 60 metres to join a Seasearch survey. Much of our coastline remains under-recorded and there are many exciting sites and species yet to be discovered.
Dr Marion Perutz came to Aberdeen to carry out a PhD at the FRS Marine Laboratory. She has surveyed un-chartered coral reefs in remote Sulawesi, mapped grey nurse shark habitat in Queensland, and identified causes of a coral disease outbreak in the Mexican Caribbean.
This is an article from the May 2008 edition of Leopard Magazine. To read much more like this every month, see our subscription details.