Beyond kelp Is seaweed our next great hope?

From food to plastics, o ocean vegetation could solve many looming production problems, say researchers

- Richard Orange MALMÖ

‘You can just see the buoys of the sea farm," Dr. Sophie Steinhagen yells over the high whine of the boat as it approaches the small islands of Sweden's Koster archipelago. The engine drops to a sputter, and Steinhagen heaves up a rope to reveal the harvest hanging beneath: strand after strand of sea lettuce, translucent and emerald green.

“This is one individual that we would collect now and keep as a parent, because it's growing very fast," she exclaims. In summer, these waters teem with sea kayaks and yachts from neighbouring Norway, but for Steinhagen and the sea farming group at the Tjärnö Marine Laboratory, spring is their peak season.

For one thing, it means less animal and plant life on the seaweed. “When you buy a lettuce, you don't want to have a caterpillar in there. The same is true for seaweed: you don't want a crab or snail eggs," she says. More importantly, spring is also when sea lettuce yields the most protein.

In fact, experts believe seaweed could be a key crop in the "protein shift” away from meat. Some of last spring's harvest here hit about 30% protein, close to the level that would make it compete against other big protein sources such as meat and soya.

Steinhagen also believes this plant - long eaten as "green laver" on the coasts of Britain - can be a more sustainable alternative to soya. Sea lettuce doesn't draw on scarce resources of land and freshwater.

"There is no other option,” she says later, on a bench outside the Tjärnö Marine Laboratory's greenhouses. "Climate change is affecting most of our crop systems and we are in urgent need of new production. We cannot extend terrestrial farmland - so we need to go into the ocean."