News: kelp! Save our hidden forests
Kelp stores carbon, enhances biodiversity, benefits commercial fishing and shields our coastlines from storms. Surely it makes sense to save this wonder seaweed?
The wonder seaweed that needs our help and protection
Consider, for a moment, the great forests of Britain. What springs to mind? The oaks and silver birches, the holly and rowan trees of our royal forests? It might come as a surprise to you, then, that Britain has twice as much forest underwater – in the form of vast kelp beds – as native woodland.
Covering an area the size of Wales, these luscious submerged seascapes are to the ocean what woodlands are to life on land: a home to hundreds of diverse creatures, from seahorses to sharks. “Kelp is a critical habitat in the amount of wildlife it supports,” says Daniel Smale, a marine biologist at the University of Plymouth.
Yet this habitat is altering with climate change. We’re already seeing this in the south, where some kelp species have been declining since the 1970s. As waters warm and storms become more extreme, the concern is that this vital ecosystem will degrade further in the coming years.
The waters off Sussex – from Brighton to Selsey – have experienced the worst losses. In the past few decades, the kelp habitat here has diminished by an excruciating 97 per cent, as commercial trawling, sediment dredging and storm damage have taken their toll. The vibrant undersea forest that once dominated 40km of shoreline, and stretched 4km seaward, has now been reduced to just a few scrappy patches of seaweed.
In response, conservationists have launched an ambitious project – backed by David Attenborough – to restore Sussex kelp. The hope is that by excluding trawlers up to 4km from the shore, the area will see a return of its once resplendent marine wildlife, including the seahorses, cuttlefish, lobster and sea bream that frequented these waters just decades ago. Restoring kelp will also bring benefits for the climate and for local fisheries. “We want this to be a blueprint for other rewilding projects,” says Sarah Ward, Living Seas Officer at the Sussex Wildlife Trust, which is leading the project with the Blue Marine Foundation and the Marine Conservation Society.
“Britain is a Goldilocks zone for kelp – it’s just right.”
Kelp are large brown seaweeds that thrive in cold, clear waters. Unlike seagrasses or mangroves, kelp have no roots and need a solid base, such as a rock or boulder, to attach to. They form dense forests along the world’s temperate and polar shorelines, but Britain is a particular sweet spot, boasting the richest kelp communities in Europe. Of the 14 species of kelp in Europe, seven are found in our waters. “Britain is a Goldilocks zone for kelp – it’s just right,” says Juliet Brodie, a seaweed specialist at London’s Natural History Museum. “We have beautiful kelp forests all around our coast.”
Within these dense watery jungles, each plant can support up to 80,000 other creatures, including worms that burrow into the kelp where it attaches to a rock, sponges that settle on the stalk or ‘stipe’ of the kelp and fish that nibble on its large floating leaves. Britain’s kelp forests can reach depths of 45m and, in spring, when there’s enough sunlight, each individual blade can grow by as much as a 1cm a day, reaching lengths of 2m.
These oversized seaweeds also happen to be one of our best defences against climate change. Cuddling our coastlines, they quell the destructive energy of waves and storms. What’s more, as one of the ocean’s most efficient forms of ‘blue carbon’ (the carbon stored in coastal ecosystems), they suck vast quantities of CO2 from the air. “In Europe, the flow of carbon into kelp forests is higher than for seagrass meadows and it’s also higher than oak and pine forests,” says Smale. Globally, algal forests can capture around 1.5–2gt of carbon per year. That’s an enormous amount – equivalent to around
20 per cent of human-produced CO2 emissions.
Around 15 per cent of the carbon captured by kelp makes its way to the deep sea via natural leaf-fall, where it is locked out of the atmosphere almost indefinitely. When kelp is damaged during a storm, it breaks up and travels, as detritus, on currents to the open ocean. Eventually, the kelp – and its carbon – sinks, and about two-thirds of it ends up below 1,000m, where it remains for centuries.
So, our kelp forests are well worth safeguarding. “The biodiversity is the one thing that we really want to protect,” says Ward, “but, of course, this has other potential benefits for carbon storage and for the fishing industry, because some of the species – the crabs and lobsters, for example – are commercially important.”
It’s not all bad news for kelp, though. As waters warm with climate change, kelp forests have begun to flourish in the north, especially around Scotland and Northern
Boosts local biodiversity, such as worms and crustaceans.
Reduces local ocean acidification and de-oxygenation.
Cuts down local eutrophication (pollution caused by an excess of phosphorus and nitrogen).
Provides coastal protection, by blunting the energy of waves and storms.
Offsets climate change – cultivating just 0.001 per cent of waters suitable for kelp farming could offset the entire emissions of the global aquaculture industry.
Produces climate-friendly animal feed: feeding cows 1 per cent seaweed in their diets can reduce their methane production by up to 60 per cent, slowing emissions from agriculture and improving animal health (find out more on p54).
Provides a healthy food source – rich in minerals, vitamins and protein. It’s also a source of alginates that are used to make cosmetics and food thicker.
Found around the UK coast, kelp creates an underwater forest environment that’s teeming with marine life.
Top left: along with kelp, seagrass offers protection for species such as the spiny seahorse. Right: trawler exclusion zones could benefit myriad marine life around our coast.
Orkney has a long history of harvesting kelp. Above: sugar kelp is common in British waters.