A common seal rests on kelp.

Kelp forests suport a huge range of UK wildlife, including otters and seals. Image: Ondrej Deml/Shutterstock.com.

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Kelp dredging in Scotland would be a 'disaster' for British coasts

A proposed plan to mechanically dredge kelp in Scotland would destroy a unique habitat, says seaweed expert Professor Juliet Brodie.

Kelp forests around Britain are as large as broadleaved forested areas on land, and they are some of the most productive ecosystems on the planet.

They support a huge variety of other seaweeds and animals, and serve as nurseries for fish species including Atlantic cod and pollock. Kelp also protects the Scottish coastline from erosion.

An Ayr-based company called Marine Biopolymers (MBL) is now seeking a licence from Marine Scotland to take kelp from the Scottish seabed using a large mechanical arm. MBL commercially extracts polymers from seaweed for use in industries including food and pharmaceuticals.

Their dredging method would harvest seaweed using a mechanical comb, making it a new industry in Scottish waters.

Prof Juliet Brodie, a merit researcher at the Museum, has been studying the seaweeds of Britain for decades, and has recently turned her attention to analysing Scottish kelps.

She says she was 'heartbroken' when she heard that the application had been made.

She says, 'Kelp forests are unique and precious. Mechanical removal of kelp from the seabed will destroy this unique habitat.  There will be no nurseries for fish, no protection of our coasts and the world will be a poorer place. We need to wake up to the destruction of these ecosystems before it is too late.'

Disturbing the sea bed

MBL claims that over five years it will start harvesting 30,000 tonnes per year of the seaweed Laminaria hyperborea, a large, leathery brown kelp.

The company propose to use a comb-like harvester measuring between three and four metres to trawl the seabed. This method removes entire kelp plants, with the idea that juvenile plants are left to promote more rapid recovery - although the evidence for this in Scottish waters is limited.

In a report, MBL said, 'Although at-sea harvesting of L. hyperborea would be a new industry in Scotland, such harvesting has been carried out sustainably for many decades in Norway, France and Iceland.'

However, researchers in Norway have investigated the effects of kelp dredging on commercially important species, and found 90% fewer young fish in harvested areas.

Existing Scottish kelp harvesting is limited to hand-cutting fronds, and ensuring that the stems and holdfasts (the part of the plant that connects to the seabed) are left intact.

The new proposed dredging method will rip up entire kelp plants, including their holdfasts.

Scottish Natural Heritage suggests that Scottish kelp holdfasts typically house between 30 and 70 different species, including worms, molluscs and anemones. In turn, these animals provide food for fish and mammals like seals and otters.

Juliet says, 'We know from our work at the Museum that this species is also threatened by climate change in the south of Britain. These Scottish populations of kelp are doing well at the moment, which could be an indication that they are resistant to the effects of warmer waters, making them even more vital to protect.'

Juliet also says that kelp dredging will also lead to a reduction of genetic diversity making kelp forests more susceptible to potential diseases and climate change.

The Sustainable Inshore Fisheries Trust has expressed concerns that the introduction of dredging could damage Scotland's reputation for high-quality, sustainable marine products. It could also drive down prices, possibly threatening the livelihoods of those who hand-harvest seaweed in the area.

Seaweeds offer food and safety from predators, and provides a nursery ground where juvenile fish can mature in safety. This image was taken in South Uist in the Outer Hebrides.


Attenborough weighs in

Sir David Attenborough has also lent his voice to the cause, speaking to Fauna & Flora International (FFI).

The naturalist and broadcaster said, 'Charles Darwin was one of the first people to recognise just how important kelp forests are for our oceans, comparing them in diversity to rainforests.

'These kelp forests - which can be found right here, around the coast of the British Isles - not only form an important part of the food chain, but also act as a vital habitat for a wide array of species. Their thick foliage offers food and safety from predators, and provides a nursery ground where juvenile fish can mature in safety.

'Look closely among the intricate stems and fronds of kelp, and you will find a range of fascinating sea life, from invertebrates such as sea stars, anemones and limpets, to mammals such as sea otters. Many of the fish species, such as cod, that are so important to us economically and culturally are also found here.

'For these reasons and many more (carbon storage being just one), it is absolutely imperative that we protect our kelp forests. It is perfectly possible to harvest them sustainably by removing their fronds while leaving the rest of the plant intact. But dredging - or indeed any kind of harvesting that removes the whole plant - is a wholly short-sighted measure that risks the wholesale devastation of our kelp beds.

'I urge decision makers to take the necessary action to protect these vital, and globally important, habitats.'

Members of the Sustainable Inshore Fisheries Trust are attending a meeting at Holyrood next week to discuss the issue with MPs, with Juliet attending in an advisory capacity.

Marine Biopolymers have been contacted for comment. In a recent report, the company said that blocks of kelp will be given time to recover after harvesting, and the amount of kelp removed from any block in a calendar year will typically not exceed 15% of the estimated kelp biomass.