We know the water is getting warmer,' says Prof Juliet Brodie, seaweed expert at the Museum. 'It has gone up on average by two degrees centigrade in British coastal waters over the last 40 years. That ...

"They are holding up a horizontal line," explains Mr Gregarsen, the managing director of Ocean Rainforest, a seaweed producer. "At every metre another line hangs down, and that's where the seaweed ...