Scientists in Cornwall, England, have found a tiny red seaweed species that has never before been formally identified, Natural England reported.
The discovery emerged during surveys of a little known natural oasis called the maerl beds, and the BBC joined the expedition to film the underwater find.
What happened?
According to Natural England, the organism is part of the Ceramium genus, also called pincer weed, and measures only a few tenths of an inch across.
The government agency noted that researchers confirmed it as a distinct species only by collecting living fragments, growing them in the laboratory, and sequencing their DNA.
For Professor Christine Maggs, a specialist in seaweed taxonomy, the identification resolves a scientific question that had remained open for decades.
"I first encountered this tiny Ceramium in the early 1980s, and I have been wondering about it ever since," Maggs told Natural England. "Natural England's surveys finally provided the missing piece of a scientific puzzle I've been trying to solve for most of my career."
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The surveys also revealed other notable species like Ulva rigida, a sea lettuce not previously confirmed in the U.K., and Bonnemaisonia clavata, a delicate red seaweed not seen in British waters since the 18th century.
As Natural England's dive team continued studying the habitat off Cornwall, BBC News journalist Harriet Bradshaw joined them in the field. During that work, researchers also found another specimen of the same Ceramium with reproductive structures that had never been observed before.
How is this helpful?
Natural England reported that maerl beds consist of pink, branching rhodoliths, which are loose, calcified red algae. They slowly build up over centuries into a complex habitat on the seafloor.
The algae grow by only about 0.02 inches a year, and some beds in the Fal Estuary could be as old as 4,000 years.
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These beds function as nursery habitat for juvenile fish and shellfish, offer shelter to many marine species, and trap carbon in their sediments.
Natural England senior marine officer Angie Gall said the habitat supports an exceptional range of life.
"We've already recorded more than 380 species living on the surface of the maerl beds, and that's only the beginning. Many more species live within the maerl itself or appear at different times of year," Gall said.
What's being done?
Since 2023, the agency and its partners have used dive surveys and seabed mapping to chart and protect Cornwall's maerl.
Natural England said that effort has also fed into the Cornwall Maerl Conservation Action Plan, which grew out of what it described as the U.K.'s first forum focused specifically on maerl.
The plan came from a forum that assembled scientists and policymakers around priorities including sustainable fishing, restoration research, and public engagement.
Natural England said researchers at the University of Exeter have used whole genome sequencing to tell apart maerl populations across southwest Britain, including a genetically unique population in St Mawes.
That work is helping shape marine management and wider conservation objectives.
"Finding species new to science in our waters is thrilling," seaweed expert Francis Bunker reflected. "But it also shows how much biodiversity is still hidden in these beds and what we stand to lose if these habitats are damaged before we've fully understood them."
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