The incredible life of Scotland's seabed revealed

He went on: “Some of the places the team visited are what scientists call ‘natural refugia’ – areas that, due to the topography of the seabed, protects marine life. They show what kind of life can form on the seabed when the routine, physical disturbance by humans is removed.”

Scotland’s seas are, to many of us, still alien and mysterious. Unlike the land, whose forests, mountains, flora and fauna are mapped in many a mind, they remain, below its calm or raging surface, relatively unknown. However, a recent project has attempted to change this and allow us to see beneath the seas’ cover – and while it may not bring the state-of-the art footage of David Attenborough’s The Blue Planet, it is strikingly revealing.

This summer, the scientific vessel, MV Sea Beaver, took a 2,500km trip across Scotland’s seas, during which it made 300 drops of remotely operated underwater vehicle (ROV) to film the bottom of the ocean and sent up an aerial drone to capture high-resolution footage from above.

What this project, run in collaboration with Greenpeace, revealed is a world at the bottom of the sea of astonishing wonder but also, in places, loss.“What we’re trying to do is bring that sea world above the water,” said Taylor. “When you see images of this damage it’s so compelling that it tells much of the story.”

Operation Ocean Witness’s research provides a series of snapshots of nature’s wonders, from phosphorescent sea pens to maerl beds, and also plays an important role in the mapping of where our most vital ecosystems are.

Maerl forms one of the most striking of these underwater marvels, as the coraline algae carpets the seabed in vivid purple-pink spikes and which, after it has died and been crushed by the waves and bleached by the sun, forms the white sands of the west coast’s most glorious beaches.

According to Taylor, these maerl beds are “the equivalent to an oak forest in terms of ecological vibrancy”. They even grow at a similar rate to oak forests, proportionately, with each calcareous spike extending by one millimetre per year. These habitats, centuries old, are key for many types of fish, including herring, juvenile cod and young scallops, as well as a blue carbon store which can lock up carbon in the seabed for a thousand years.

“Certain fish,” Taylor noted, “appear to use maerl beds specifically to spawn, for example, herring have been observed spawning on maerl in Loch Gairloch. Scientific research is ongoing, but it may be that the complex structure of maerl simultaneously shelters and helps oxygenated water flow around the eggs, enhancing their chances of survival.”

But maerl is disappearing – not just in Scotland, but elsewhere. Loch Fyne off the Firth of Clyde, for instance, has lost 10 per cent of its maerl beds. This pink seaweed is fragile and easily damaged by physical impact and one French study that looked into the effects of dredge fishing in the Bay of Brest found that disturbances associated with “extraction and/or fishing activities using mobile bottom-contacting gears such as clam-dredges” induced “the most severe and long-term effects on these fragile habitats.”

Climate change is also having an impact. Researchers from Heriot-Watt University created a computer model which predicted that even in a best-case scenario, where emissions are rapidly reduced, Scotland’s maerl bed distribution seems likely to shrink by 38% by the end of the century.

Off Orkney came another bucket-list experience – the appearance of a flapper skate, gliding, ghost-like, through the grey. Flapper skates, which can grow to a wingspan of three metres, are critically endangered and on the International Union for Conservation of Nature’s red list – and are therefore at greater threat of extinction than the giant panda – yet this shark-related species was once called the “common skate”.

“Just like China is a stronghold for pandas,” said Taylor, “Scotland is a stronghold for flapper skate and after years of decline we are beginning to see signs of population recovery, but such a slow-growing creature that hunts on the seabed is susceptible to being caught as by-catch in bottom-trawl fisheries.”

Their egg cases are also easily damaged by physical impact. The largest egg-laying site known in the world happens to be in the Inner Sound of Skye. After it was discovered in 2019 by divers – who counted over 100 egg cases – Marine Scotland set up an urgent Marine Protected Area at Red Rocks and Longay, in certain areas of which it is illegal to fish using towed gears. But will it remain so? A consultation took place earlier this year to make this prohibition permanent.

Another marvel was seagrass and, around the Isle of Gigha and near Papa Westray, the team helped map the location of seagrass meadows by “stitching” together high-resolution images taken by aerial drones.

Unlike seaweed, which is an algae, seagrass is a marine plant, which roots itself in the sand, has small green scale-like flowers and produces seeds, and provides a habitat rich in biodiversity – sheltering young fish and invertebrates. Seagrass meadows are not just pretty, they also, significantly in these climate-crisis times, sequester carbon.

“Once widespread,” blogged Dr Rohan Holt, a team member on Sea Beaver, “it suffered massive declines and now struggles to survive where pollution, disturbance from anchors, moorings and fishing gear slows its growth and rips up the plants.”

How much it has declined is much debated. Holt quoted a loss of 44% in UK waters since 1936. Dr Richard Lilley of the seagrass restoration charity Project Seagrass has described it as “probably at least 50%”. What is clear, however, is that we can only protect this habitat when we know it is there. This is why projects like Sea Beaver’s mapping, and citizen science work done by Project Seagrass, are significant.

As well as these remarkable finds were others, such as billowing kelp fields, phosphorescent sea pens, dead man’s fingers, a curled octopus camouflaging itself in rocks. “What we found,” said Taylor, “ is that, where there are measures in place to protect the seabed, it works.”

Not every ROV drop, however, brought such vibrancy – nor did every protected area seem properly protected. Footage from only last month also revealed severe damage to marine life and habitats by scallop dredgers in the Small Isles Marine Protected Area (MPA). The protected area was set up in 2014 to conserve Britain’s only colony of fan mussels and other features. It is one which Open Seas had visited as recently as 2020 and found in good health.

“We were involved in a survey with highly experienced divers in 2020,” said Taylor, “and encountered healthy seabed habitat north-west of Rum within the Small Isles Marine Protected Area. Just a couple of months ago, we returned to the Marine Protected Area and found scallop dredge tracks scarring the seabed. This shows there is damage going on in areas that are called protected areas.”

For Taylor, the Small Isles MPA is as “a very clear example of a paper park, an area of public seabed that government claims is protected, but where no fisheries management has been implemented and marine habitats are still being degraded, legally.”

The Scottish Government has committed to designating Highly Protected Marine Areas covering at least 10% of Scotland’s inshore and offshore waters before the end of the current parliamentary term.

But, as Operation Ocean Witness shows, we are a long way from providing adequate protection. “Until the 1980s,” said Taylor, “there was a sensible limit on bottom trawling within three nautical miles of the shore. It protected small-scale fisheries and the seabed itself. Like many others, we’re calling for a reinstatement of some form of inshore limit on bottom-towed fisheries to give our seabed a chance to recover.”

The campaign group also want to see “proper tracking on all vessels to ensure marine protected areas are being complied with and so fishery managers can understand and better regulate the footprint of fishing”. And, according to Taylor, most important of all is that government “should be giving preferential access to sustainable fishing”.

“There are fisheries and areas of seabed,” he said, “that can be harvested in different ways, and if one is lower impact than the other then we should be having a policy that ensures that lower-impact method of fishing is given priority.”

Without such measures what will our seabeds look like in 50 years? Will giant skates still glide through an ocean whose floor is encrusted with shimmering pink?