One of Earth’s most biodiverse habitats lies off the Scottish west coast – but climate change could wipe it out


Lukassek/Shutterstock

Heidi Burdett, Heriot-Watt University and Cornelia Simon-Nutbrown, Heriot-Watt University

Maerl beds stud the ocean floor like underwater brambles. They’re pastel pink and, despite their knobbly appearance, made up of a red seaweed. This algae has a limestone skeleton which gives it a complex three-dimensional structure that is quite unlike the slimy seaweeds you may be more familiar with.

In fact, the closest thing to a maerl bed you’ve probably heard of is a coral reef. Like tropical reefs, the seaweeds in maerl beds interlock as they grow, creating nooks and crannies that serve as the perfect home for a huge range of sealife. Maerl beds are one of the world’s most biodiverse habitats, but unlike coral reefs, few people have heard of them and even fewer study them.

Also known as “rhodolith beds”, maerl beds are found in coastal waters all over the world, from the poles to the equator, but pockets of this habitat form European strongholds off Scotland’s west coast and islands. Sadly, our new research has revealed how climate change threatens to destroy much of this natural heritage before its wonders have been brought to light.

A clump of knobbly, pink, coralline seaweed.
A piece of Scottish maerl that is well over 100 years old.
Nick Kamenos, Author provided

Climate change and maerl beds

Maerl grows at a glacial pace – just 0.2 mm per year in Scotland. This makes it difficult for these habitats to respond to rapid changes in water temperature or ocean currents. But these are just the kind of environmental changes that are expected around Scotland over the coming century.

Until recently, scientists had only conducted small-scale experiments on maerl, so we knew very little about how Scotland’s beds would respond to climate change. To overcome this, we developed a computer model that can predict how the multiple changes to Scotland’s climate will affect the distribution of this habitat by 2100.

Astonishingly, even in the best-case scenario, where emissions are rapidly reduced from current levels, we predict that maerl bed distribution will shrink by 38% by the end of the century. If global emissions stick to their current trajectory, we predict a massive 84% decline in maerl bed distribution around Scotland. Without major changes we will likely follow this path, or worse.

Our research tells us that this would be devastating for the flora and fauna that call this habitat home, including commercially important species such as juvenile pollack, hake and scallops.

Scotland’s maerl beds under ‘worst-case’ warming scenario

Two maps comparing maerl bed distribution off the Scottish coast today and in 2100.

Simon-Nutbrown et al. (2020), Author provided

Refuge areas

Only international efforts to rapidly reduce greenhouse gas emissions could improve the situation for Scotland’s maerl beds. But managing the coastal ocean better – with regulation of trawling and pollution – could soften the blow. Since our model found that the rate of habitat decline will be fastest between now and 2050, the need for rapid action is even more urgent.

It’s unrealistic to expect the entire coastal ocean of a country to be placed under strict marine protection. After all, these regions are very valuable to a range of industries and interests, like tourism, shipping and fishing. Where then, should we focus our efforts? Our computer model helps with this too.

We have identified some key areas in which maerl populations are likely to persist in local micro-climates. Here, temperatures are not predicted to rise as much as the surrounding water and changes in waves and currents at the seafloor are expected to be less pronounced. This will allow maerl beds to remain in areas such as Loch Laxford, mainland Orkney and mainland Shetland. Protecting and monitoring these refuge areas could maximise the chances of these habitats surviving for future generations to enjoy.

Seafloor habitat with pink clumps of maerl, rocks and seaweed.
A Scottish maerl bed brimming with life.
Nick Kamenos, Author provided

Knowing where a habitat might continue to thrive in the future is crucial for planning how to manage coastal seas better, and being able to map these areas can help reconcile their protection with other activities. The refuge areas we found will now be considered as priority conservation areas by the Scottish Government.

Climate change is expected to affect maerl beds all around the world, so the computer model we’ve created can now find other areas where they may be able to cling on globally. Conservation can be long, gruelling work, so being able to focus marine protection efforts in areas with the highest chance of survival could help safeguard at least some of this habitat for future generations.The Conversation

Heidi Burdett, Research Fellow, Lyell Centre for Earth and Marine Science and Technology, Heriot-Watt University and Cornelia Simon-Nutbrown, PhD Candidate in Marine Conservation, Heriot-Watt University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Monster hunt: using environmental DNA to survey life in Loch Ness


File 20180624 26576 1k61oxw.png?ixlib=rb 1.1
With the help of environmental DNA, scientists are compiling a census of life in Loch Ness, which should establish if there is any scientific basis to the centuries-old legend of the Loch Ness monster.
Supplied, CC BY-SA

Neil Gemmell

Reported sightings of the Loch Ness monster go back to the Dark Ages, but now our Super Natural History team is using the 21st-century technology of environmental DNA to survey all life in the famous Scottish lake.

The premise of environmental DNA (eDNA) is simple. Life is messy, and living things leave behind skin, hair, feathers, poo, bark, pollen and spores as part of their day-to-day activities.

These traces result in a potpourri of organic material in our soil and water from which DNA can be extracted and sequenced. Our aim is to produce a census of life in Loch Ness and to establish if there is any scientific basis for the centuries-old monster legend.




Read more:
Why won’t scientific evidence change the minds of Loch Ness monster true believers?


Sampling a legend

There have been more than 1,000 registered sightings of the Loch Ness “monster”, including two in the last month. They have sparked various theories. Some say the loch is home to a prehistoric relic, while others believe it’s a giant sturgeon, catfish, or just a log or a boat wake.

Obviously, the hook here is that if Nessie is present in the deep, dark and mysterious waters of Loch Ness (for the record I am not a believer, but open to being wrong) then we might find DNA sequences that will help us figure out its biological basis.

We have now finished two weeks of field work for this project, having collected 259 water samples from various parts of the loch, including its chilly depths, more than 200 metres down.

The team took water samples from several sites on the lake, as well as from deep waters.
Kieran Hennigan, CC BY-SA

Miraculously, for the Highlands, the wind stayed light and the rain stayed away which meant we were able to send teams out to sample right around Loch Ness by car and small boat, as well as several nearby lochs as controls. We have also used the Loch Ness Centre boat to sample up and down Loch Ness, particularly targeting the loch’s depths.

Decoding life

Our days were long, frequently starting as early as 6am and finishing as late as midnight. Our project was also hard on equipment – we broke two of our three sampling devices deploying to depth. Now, with sample collection behind us, we are onto the next phase of work.

The DNA is currently being extracted from our filtered water samples at the University of Hull. From there it will go to French and Swiss laboratories to be metabarcoded and sequenced.

What will we find? Well undoubtedly there will be DNA sequences derived from bacteria, protists, algae, invertebrates, and the traces of fish, birds and other vertebrate life known from the loch.

What we’ll get is a comprehensive survey of the biodiversity of Loch Ness, but whether we’ll find anything unusual, such as a giant catfish, sturgeon or eel, or a species unknown to science, who knows. Nessie believers will have to wait a few more months for the final results.




Read more:
Bigfoot, the Kraken and night parrots: searching for the mythical or mysterious


It all started with a tweet

About two years ago Darren Naish had just published a book, Hunting Monsters, which included a section on Loch Ness. Over a few tweets I asked him if, in his research for the book, he had stumbled on anyone who was using eDNA to search for evidence of Nessie. The answer was no, but we both thought it a splendid idea.

I was becoming increasingly enamoured with the power of eDNA as a means to monitor the natural environment. Our team at the University of Otago was undertaking eDNA work that demonstrated amazing accuracy at identifying the species that resided in the marine ecosystems we studied.

Based on this, I was already thinking about how we might use eDNA to search for and identify the creatures that live in areas of our planet that are hard to investigate using traditional approaches – deep oceans, subterranean water systems and the like. Loch Ness seemed a perfect fit for that sort of project.

Career killer or opportunity?

As with many science ideas, that tweet ended up going into the “this is quite interesting” basket and there it sat until I got an email from Scottish journalist John Paul Breslin. When his article appeared in early April, many took it for an April Fool’s joke, but the story rapidly spread from Scotland to the rest of the world.

The media interest was overwhelming but I wasn’t sure if this was something I really wanted to do. At the time I was the head of a large department at a respected university, with an international reputation for doing quality work in the areas of molecular ecology and evolution. Some colleagues suggested the idea might be a career killer.

The turning point arrived one morning when I was dropping my son off at school. A large posse of eight- and nine-year-olds told me they thought the idea of hunting for the Loch Ness monster was the coolest thing ever. It resonated with me and led to this opportunity to engage the public, particularly kids, in the scientific process.

Loch Ness expert, Adrian Shine (right), had dredged the deep lake many times and is now helping to sample DNA traces of life.
Kieran Hennigan, CC BY-SA

One of the first stops was Loch Ness expert, Adrian Shine, who had dredged Loch Ness many times with nets and other devices and agreed to provide a boat and skipper. Several other colleagues all agreed to join the project and the team grew as we realised the Loch Ness monster hunt would describe the biodiversity of the lake in unprecedented fashion, add information about the movements of migratory fish species such as salmon, eels and lamprey, and be a hell of a science communication platform.

The ConversationSo, our project is not a simple monster hunt (although wouldn’t it be amazing if we did find something extraordinary during our investigation). Rather it is an amalgam of basic science, linked to major current initiatives, with a strong science communication aspect. Ultimately, we may find no DNA evidence that explains the monster myth, but I doubt that will ever dent belief. As Adrian Shine quips, absence of evidence is not evidence of absence, and those that wish to will continue to believe in monsters.

Neil Gemmell, Professor of Reproduction and Genomics

This article was originally published on The Conversation. Read the original article.