Underwater power cables are ‘mesmerising’ brown crabs and causing biological changes that could affect their migration habits, scientists warn 

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  • Scottish experts find high level of electromagnetism in brown crab
  • This electromagnetism has caused cellular changes, affecting their blood cells.
  • The brown crab has been described as the most commercially important crab in Europe.

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A new study shows that underwater power lines laid along the ocean floor for offshore wind farms are ‘enchanting’ brown crabs and causing biological changes that could affect their migration habits .

Experts in Scotland triggered ‘behavioral and physiological responses’ from exposure to electromagnetism in about 60 brown crabs at St Abbes Marine Station.

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This causes cellular changes in the crab species, affecting blood cells and possibly making them more prone to infection, they warn.

Oddly, cables for offshore renewable energy also emit an electromagnetic field that attracts the crabs and makes them immobile, which affects reproduction and migration, according to the team.

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The brown crab (Cancer pagurus, pictured), also known as the edible crab, is the most commercially important species of crab in Europe.

brown crab

The brown crab, also known as the edible crab, is the largest species commonly found around the British Isles.

It has a particularly large black-tipped claw and a ‘pie-crust’ edge to the shell which makes it easily recognizable.

Males can weigh up to three kilograms.

Crabs are generally nocturnal, scavengers and forage for food under cover of darkness and adults are found underwater to depths of 100 m.

Tests have shown that the claws of edible crabs have a crushing power of over 90lb per square inch – an average person’s hand is only capable of crushing 25lb per square inch.

If a crab loses a claw, they can re-grow it over the course of several molts, which is when a crab sheds its exoskeleton for a new one, but it may be smaller or weaker than the original. Is.

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The brown crab (Cancer pagurus) is the largest crab species in British waters and is still sought after by seafood fans for its delicate and sweet taste.

According to the Wildlife Trust, it is the most ‘commercially important’ species of crab in Europe, with 10,000 tons harvested from the English Channel each year.

Therefore any negative impact on their breeding and migration can drastically affect population numbers and stocks.

Study author Alastair Linden at Heriot-Watt University said: “Underwater wires emit an electromagnetic field.

‘When it’s at a strength of 500 microtesla and above, which is about 5 percent of the strength of a fridge door magnet, the crabs are attracted to it and just settle down.

‘That in itself is not a problem. But if they are not moving they are not looking for food or a mate.

‘Changes in activity levels also alter sugar metabolism – they store more sugar and produce less lactate, like humans.’

The researchers used the St. Abbes Marine Station’s purpose-built aquarium laboratory for the experiment.

“The aquarium lab is made entirely of non-metallic materials, which means there is minimal electromagnetic interference,” said Kevin Scott at St. Abbes Marine Station.

The electromagnetic field strength of 250 microtesla was found to have ‘limited physical and behavioral effects’.

However, exposure to 500 and 1000 microtesla was found to disrupt the circadian rhythm and alter the total hemocyte count. In invertebrates, hemocytes are cells that form hemolymph, a fluid similar to blood.

In the photo a power cable is being laid at an offshore wind farm.  Cables for offshore renewable energy emit an electromagnetic field that attracts crabs and causes them to sit quietly

In the photo a power cable is being laid at an offshore wind farm. Cables for offshore renewable energy emit an electromagnetic field that attracts crabs and causes them to sit quietly

electromagnetic fields

The electric and magnetic fields together are called electromagnetic fields or EMFs.

EMF is part of the spectrum of electromagnetic radiation that extends from static electric and magnetic fields through radiofrequency and infrared radiation to X-rays.

All populations are now exposed to varying degrees of EMF, and levels will continue to increase as technology advances.

Source: WHO / US Government

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“We found that exposure to high levels of electromagnetic field strength changed the number of blood cells in the crabs’ bodies,” Scott said.

‘This can have many consequences, such as making them more vulnerable to bacterial infections.’

The team warns that changes in the species’ behavior could affect fishing markets, as the crab is the UK’s second most valuable crustacean catch and the most valuable inshore catch.

A number of offshore wind farms are installed and planned around the coast of Scotland, which require extensive underwater cabling, and the researchers said further work is needed to ensure that they support Scotland’s brown crab population. do not destabilize.

Lyndon said, ‘Male brown crabs migrate to the east coast of Scotland. ‘If it proves too difficult to resist laying miles of underwater cable, they will stay.

‘This could mean that we have a buildup of male crabs in the south of Scotland, and a lack of them in the north east and islands, where they are incredibly important to fishermen’s livelihoods and local economies.’

One solution, he said, would be to bury the cables in the ocean floor, but this could be costly and make maintenance more challenging. This also cannot be done in some places.

“We need to investigate more technical solutions so that we don’t create negative environmental impacts when trying to decarbonize our energy supplies,” Linden said.

Researchers say the revelations are necessary for policy making, environmental assessment and understanding the effects of electromagnetic fields on marine life, including the brown crab.

Buried deep beneath the world's oceans and seas is a network of underwater cables for power transmission (stock image)

Buried deep beneath the world’s oceans and seas is a network of underwater cables for power transmission (stock image)

The species is found throughout European waters, with a distribution ranging from Norwegian waters down to …

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