The team from Heriot-Watt University showed that the electromagnetic field emitted from undersea power cables affects the crabs’ biology at a cellular level and stops them from moving.

Researcher Dr Alastair Lyndon said: “When it’s at a strength of 500 microTeslas and above, which is about 5 per cent of the strength of a fridge door magnet, the crabs seem to be attracted to it and just sit still.

“That’s not a problem in itself - but if they’re not moving, they’re not foraging for food or seeking a mate. The change in activity levels also leads to changes in sugar metabolism: they store more sugar and produce less lactate, just like humans.”

The scientists observed around 60 crabs at the St Abbs Marine Station in the Scottish Borders and used its purpose-built aquarium laboratory for the experiment.

Dr Kevin Scott at St Abbs Marine Station said: “The aquarium lab is composed entirely of non-metallic materials, which means there is minimal electromagnetic...