Nature
A 40-Year Mystery Solved: New Pink Seaweed Species Confirmed off UK Coast
In the 1980s, a marine biologist collecting seaweed samples off the coast of Northern Ireland noticed something unusual: a delicate pink seaweed that did not match any known species. For decades, the specimen sat in a collection, labeled as a curiosity. Now, after years of painstaking genetic and morphological analysis, scientists have confirmed that it is a new species — Ceramium ruenessianum, named in honor of the researcher who first studied it.
The new species belongs to the genus Ceramium, a group of red seaweeds known for their fine, branching filaments. Unlike many newly described species, which are often microscopic or discovered in remote tropical locations, this one was hiding in plain sight — growing on maerl beds off the coast of Northern Ireland, in waters that have been studied by marine biologists for generations.
How it was confirmed
Professor Christine Maggs of the University of Galway, who first encountered the seaweed decades ago, never forgot it. Advances in DNA sequencing technology finally made it possible to compare the mysterious pink seaweed with related species at the genetic level. The analysis confirmed that the seaweed was genetically distinct, with a unique combination of traits that set it apart from all other known Ceramium species.
The species grows on maerl — a type of free-living calcified seaweed that forms brittle, coral-like beds on the seafloor. These maerl beds are biodiversity hotspots, providing habitat for hundreds of marine species, and the discovery of a new seaweed species within them highlights how much remains to be discovered in even well-studied coastal ecosystems.
Why it matters
Biodiversity in plain sight. The discovery of a new species in a region that has been studied for centuries underscores how incomplete our knowledge of marine biodiversity remains. Many species may be overlooked simply because they resemble more common relatives.
Maerl beds need protection. Maerl habitats are slow-growing and fragile, taking centuries to form and easily damaged by bottom trawling, dredging, and pollution. The discovery of a unique seaweed species within these beds adds to the conservation case for protecting them.
Public naming invitation. The species is so new that it does not yet have a common name. The Natural History Museum has invited the public to suggest one, engaging a wider audience in the process of scientific discovery.