Scientist's lifelong obsession with mystery of elusive 'pink zebra' seaweed

The Great Barrier Reef might be the world's most famous underwater ecosystem, but hidden in UK waters lies an ancient marine world you may not have heard of.Known as maerl beds, these carpets of coral-like seaweed create some of the richest habitats in the sea.And 40 years ago, while studying one such bed for her PhD, Prof Christine Maggs found a fragment of pink-striped seaweed living on maerl she had never seen before.The discovery would become a lifelong obsession and a decades-long scientific puzzle.Image source, Francis BunkerImage caption, New ceramium is an entirely new species unknown to scienceMaerl beds may closely resemble corals but they are in fact thousands of pieces of free-living calcified seaweed that can interlock to create a carpet brimming with life.Hours of trawling through the literature seemed to confirm that no-one else had known what this little seaweed that lived on maerl was either. Prof Maggs suspected it was a new species to science.But she needed a larger piece for a formal identification.She continued the hunt after her PhD, and the tiny seaweed would accompany her throughout her career, with fleeting glimpses including once on an underwater animal called a sea squirt, although never enough material to pin its identity down.Image caption, The Natural History Museum collection of seaweed pressings which the new species has joinedBut then two years ago, researchers surveying maerl beds in Cornwall found a sample, which they thought might be Prof Maggs' elusive seaweed.Prof Maggs bought a wine fridge in anticipation, the perfect dark, cool environment to store it while tests were carried out to prove it was, indeed, a new species."I just kept hoping that I would find out, it's been over four decades," she said.She has now shared the discovery exclusively with the BBC, and a sample of the species has joined the Natural History Museum's official collection.Image source, Angie GallImage caption, Maerl bed in the Fal estuaryThe scientific divers who found the sample were mapping and analysing seaweeds to check on the health of Cornish maerl beds, a project organised by Natural England.This type of diving is specialised and expensive, involving difficult logistics and a large amount of equipment. But for the researchers involved, the experience is extremely rewarding."It's magical. You're just at one with nature and in your own little world really," Dive Officer Lucy May says.They have seen spider crabs taking a stroll, starfish, king scallops and goby fish.Amongst the collection of bags brought up on one such Cornish trip were cuttings of a small red algae which was pink-banded with pincer tips.Image source, Prof. Curt PueschelImage caption, Christine Maggs in 1982 in a home-made drysuit with her PhD supervisor Mike Guiry beside herFrancis Bunker, a freelance and independent marine biologist, kept finding the tiny seaweed in samples he had collected on that survey."I suppose you've got to be a bit nerdy," he says, explaining he takes a magnifying glass with him diving. "You've got to be awed by it all, which I never cease to be."He suspected the tiny seaweed might be what Prof Maggs had long been searching for. He gathered as much as he could and sent it to her in London.Prof Maggs needed to grow the seaweed big enough to be DNA sequenced. She turned to her trusty cool chamber - the wine fridge."This particular seaweed is so small I needed to get some molecular data," Prof Maggs explains. "That's why this has taken me 40 years."Image source, Francis BunkerBut the wait was worth it. With the help of Prof Beatriz de Barros Barreto, who worked on the DNA sequencing, Prof Maggs has put the pieces of the puzzle together to reveal the seaweed is indeed new to science."We knew that maerl was a rich, biodiverse habitat, but we didn't necessarily realise that we'd be still finding new species that live on that maerl," Prof Maggs says."It's great," Bunker adds. "I think it's what spurs you on really, finding a new species. It's like the icing on the cake, or the cherry on top."Prof Maggs' findings are soon to be published in the peer-reviewed journal Phycologia.Image caption, Professor Christine Maggs at workSeaweeds are one of the most ancient forms of life - having developed more than 1bn years ago - and many provide a critical food source for fish and a haven for them to lay their eggs.For humans, the abundant minerals and anti-inflammatory properties of certain seaweeds have seen their extracts used in medicines from treating acid reflux to wound dressings."We really have to look after seaweeds, we really have to love them," Prof Juliet Brodie, a leading seaweed expert, explains in the vaults of the Natural History Museum surrounded by a collection of seaweed pressings the new species is joining.Finding a new species, although exciting in itself, plays an important role in keeping an eye on the maerl's health over time."They're really precious," she adds. "I've often pondered to myself, what would the world be like without seaweeds? You would be taking away your nurseries for some of your economically important fish. But you would also [remove] the immense diversity that makes our world function."Image caption, Scientific divers on a maerl siteProf Craig Schneider, professor of biology at Trinity College Connecticut, who was not involved in the study, says the discovery of the new species is "significant" to science.He said it could also add to interest in protecting maerl beds, which were "already of the greatest importance to all of the other plants, animals and microbes in the ecological community that they support".Maerl beds are rare in Britain. They are classed as a threatened and declining habitat under the OSPAR convention - an international agreement for environmental protection in the North-East Atlantic.There are currently four protected maerl sites in the UK, including the Fal and Helford Special Area of Conservation (SAC).But the less studied beds off the south Cornish coast, where the new species has also been found living on the maerl, are not formally protected.Image source, Natural EnglandImage caption, A spotted skate on maerl and a spider crabDefra says it may not be necessary to make this area of maerl beds an SAC, "nor is there a requirement, to protect all examples of a species or habitats."Part of the reason, it says, is balancing nature recovery with "wider priorities including offshore wind development and fisheries."Whilst protection is debated, the researcher-divers continue their work to document and potentially recover new species, and perhaps the most exciting part, to name them.Image source, Francis BunkerImage caption, New species growing on maerlProf Maggs' new species will be known scientifically as ceramium ruenessianum, in honour of her colleague who has studied this type of species for the last 40 years.As for the seaweed's common name, a firm favourite amongst the scientific divers is "pink-zebra weed".Other ideas include "pink-banded bandit" and "ribbon claw". Prof Maggs is inviting the public to make their suggestions.EnvironmentSeaweedConservationNatureScience & Environment