Work starts to protect rare ‘carbon capture’ seaweed discovered off the coast of Cornwall

The rare seaweed provides protection for many small marine plants and animals. Credit: Lewis Jeffries

One of the largest amounts of a rare type of seaweed ever discovered in the UK has been uncovered off the coast of Cornwall.

The vast seabed of maerl, a rare and ancient seaweed, is equivalent to the size of nearly 900 rugby pitches and is thought to be around 4,000 years old. It carpets the seafloor and provides protection for many small marine plants and animals.

Scientists discovered the seaweed in the Fal and Helford Estuary Special Area of Conservation

It is extremely efficient at storing carbon at an estimated rate of 841 tonnes of CO2 every year, the equivalent to nearly 4,000,000 petrol car miles a year and five times greater than that absorbed by the combined area of seagrass, kelp and saltmarsh also in the same area.

It is the first time the full extent of the maerl beds and the organic matter stored in the conservation area has been measured with the discovery now marking the location as a key national site.

Dr Chris Laing, Senior Lecturer in Marine Biology at the University of Exeter and research lead on the project said: "Maerl has not been considered as a valuable carbon store to date.

"Our research demonstrates that as well as being a rare and valuable seabed habitat it should be a key player in coastal blue carbon assessments which is an extremely important discovery for Cornwall where the extent of the maerl beds are significant.”

Work is underway to find the best way to protect the seaweed Credit: Lewis Jeffries

Cornwall Council is now working with the university and other partners such as Falmouth Harbour Commissioners and Ocean Conservation Trust to protect the valuable ecosystem from threats such as anchor damage, swing moorings, nutrient discharge and sea surface temperature increases from climate change.

Cornwall’s cabinet member for environment and climate change Cllr Martyn Alvey said: “The project shows how these blue carbon habitats can help us in our response to both the climate and ecological emergencies if we properly protect them and allow them to fully recover.

"We are working with partners to ensure that these vital blue carbon ecosystems are protected from threats such as poor water quality, recreational boating and nutrient loading.”