Underwater surveys of maerl beds off the south coast of Cornwall uncovered rare seaweeds, including species never before recorded in the UK, Natural England reported on 1 August 2026. Among the findings was a tiny red Ceramium (pincer weed) only a few millimetres across, confirmed as completely new to science after divers brought living fragments to the surface for lab cultivation and DNA sequencing.

The surveys also recorded Ulva rigida, a green sea lettuce never previously confirmed in the UK; Neofolia rosea, found only once before in the UK at the same site; and Bonnemaisonia clavata, a red seaweed last seen in British waters in the 18th century. Natural England senior marine officer Angie Gall said more than 350 species had been recorded on the surface of the maerl beds, with many more still to uncover. Seaweed expert Francis Bunker, who found the minute Ceramium, said the discoveries show how much biodiversity remains hidden in these beds. Professor Christine Maggs, a seaweed taxonomy authority, said she first encountered the tiny Ceramium in the early 1980s and that the surveys completed a puzzle she had worked on for most of her career.

The work followed reports from citizen scientist divers on the Seasearch project; Natural England said its surveys in 2023 and 2024 found extensive previously unknown maerl beds off England's south coast. The agency noted that physical disturbance such as scallop dredging, pollution and climate change pose ongoing threats to maerl beds.