In the 1980s, so much kelp washed onto beaches west of Brighton that the “unsightliness” of the seaweed and the flies it attracted made it a problem worthy of . Farmers took the abundance of washed-up brown algae for fertiliser. Locals talked of the “kelp problem”. Today, the problem is too little kelp, says Mika Peck at the University of Sussex, UK.
Kelp matters because it , provides a nursery for fish and a buffer against coastal flooding. While climate change has played a role in kelp’s decline around the world, . For this stretch of England’s south coast, several theories have been floated but not proven, including the Great Storm of 1987 and damage by fishing trawlers. That led campaigners to fight and win . The evidence underpinning that ban will be reviewed in five years’ time.
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Peck now hopes to find out whether kelp can recover, and if trawling really was the culprit. “This is definitely a nature-based solution to address both climate and biodiversity issues,” says Peck, as he sways aboard a workboat leaving Shoreham Harbour on 15 July. “On our doorstep, we’ve got a way of regenerating a biodiverse environment as interesting as a tropical rainforest far away.”
To create a baseline survey of the kelp hidden many metres below the waves here, from Shoreham in the east to Selsey in the west, Peck has turned to low-cost techniques he pioneered for a very different environment: coral reef in Papua New Guinea. Luckily for the crew today, the weather is mostly gloriously still and sunny. Unseasonably bad weather earlier in July postponed some survey days.
Offshore from the pavilion of a holiday camp in Bognor Regis, the boat slows as Peck’s team reaches the GPS coordinates for one of 28 sites they are surveying. At a blast of the ship’s horn, Peck works hands-on with his team. In quick succession, they drop three baited remote underwater videos (BRUV) – GoPros and hydrophones plus fish bait attached to a system of metal bars that resemble an athletic hurdle – which cost roughly £2000 each. The team is also trialling a lighter, cheaper “baby BRUV” costing closer to £200, but the jury is out on whether its camera is up to the task.
All the footage captured will be analysed to give a picture of the kelp’s extent, health and diversity. They expect to see sugar kelp (Saccharina latissimi) and oarweed (Laminaria digitata and Laminaria hyperborea), which are less forest-like than some more structural species found further west.
The traditional video surveying will be paired with the more unconventional audio recordings from the hydrophones. Peck has previously found a link between healthy tropical reefs and certain types of soundscape. Whether that holds true for south England’s temperate waters remains to be seen – at the least, it should give an indication of the habitat on the seabed, be it rocky or sandy.
The third leg of the survey takes place in the lull as we wait an hour to haul the BRUVs back aboard. Kat Bruce of biodiversity monitoring firm NatureMetrics watches as researchers use her kit to capture fragments of environmental DNA (eDNA) that marine life shed, filling a flask with seawater and patiently pumping it through a plastic disc a little bigger than a £2 coin. “The water is a soup of genetic material,” says Bruce.
The DNA will be sent to a lab for sequencing and matching against a library of known species. You wouldn’t know how diverse the marine life is here from looking at the opaque blue-green water. But five initial samples have already detected 44 species of bony fish, from cod, plaice and goby to the odd-looking lump fish (Cyclopterus lumpus). The results of the eDNA surveys should yield a baseline to see if biodiversity grows as the kelp return.
Today’s survey is just one of many by Peck and the team this month. And it won’t end there: the plan is to repeat it every July until the review of evidence underpinning the ban in five years’ time. “The dream is basically to come back to a healthy ecosystem,” says Peck. The data should definitively show whether trawling is to blame, which could make a stronger case for more bans to give kelp a chance.
Further research is planned to see how much carbon the kelp in this area locks away. And Peck’s team is also looking at whether they can go beyond natural restoration, potentially by growing kelp spores in labs and seeking licences to actively sow them, much like .
The fate of kelp in this small patch of the south of England might seem irrelevant in the global scale of climate change. However, world leaders are waking up to the fact they will need a vast mosaic of these natural ways to lock up carbon and avert catastrophic temperature rises. Nearly 200 countries at a major UN biodiversity summit later this year are expected to agree nature-based approaches must sequester billions of tonnes of CO2 a year. Once viewed as a problem, kelp is increasingly looking like a solution.
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Article amended on 17 August 2021
We have corrected the length of the ban on nearshore trawling
