Speakers and delegates at the recent 'UK Maerl Forum', the first international event of its kind, were left in sombre mood after a dive organised to explore the maerl beds revealed a worrying deterioration in these ancient habitats.  

Participants from across the UK, Ireland and Brittany had gathered in Cornwall to hear talks from UK experts on local maerl beds. Long underappreciated, maerl is increasingly recognised as a irreplaceable marine habitat - acting as a nursery for commercial fish and shellfish species, as well as a vital carbon store.  

Matt Slater, Marine Conservation Officer at Cornwall Wildlife Trust, said: 

“It was a shocking sight. The area, which was previously purple and beautiful, is now covered with a thick layer of brown, fluffy algae. We’ve surveyed here regularly for the past eight years and I have never seen the maerl beds looking like this. It’s a massive concern and shows, yet again, why it is urgent that we do all we can to improve water quality in the Fal estuary.” 

Organised by Cornwall Council and Natural England, the forum aimed to increase collaboration and create an action plan for the protection of Cornwall’s maerl beds. The event was supported by a steering committee with representatives from University of Exeter, University of Plymouth, Cornwall Wildlife Trust and Blue Marine Foundation. 

Angela Gall, Marine Senior Officer with Natural England, said: 

“It was a pleasure to welcome speakers from far and wide to share their knowledge and experience of maerl beds in other areas - and to put into context just how special and fragile our maerl beds in Cornwall are. Their insights reinforce the urgent need for collaborative conservation efforts to safeguard these invaluable ecosystems for future generations.” 

Unfortunately, maerl beds are under threat from a variety of human activities, including towed fishing gear, anchor damage and commercial extraction. Protections such as ‘EU Special Area of Conservation’ apply within the Fal estuary, meaning mobile fishing gear and maerl extraction are both now banned. However, the conference highlighted that water quality is also a key threat. Raised nutrient levels, caused by sewage or agricultural run-off, can lead to algal blooms that smother the beds. In other areas, such as Milford Haven and Brittany, this has reportedly led to severe decline, and in some cases complete loss, of maerl habitats. 

Dr Chris Laing of the University of Exeter said:  

“Strong links have been identified between reduced water clarity and nutrient levels, and increased macroalgal growth that outcompetes photosynthesising species such as seagrass and maerl. This recent discovery is concerning and suggests urgent intervention in catchment water management is needed.” 

There are many reasons why we need to clean up our estuaries and coastal waters but the impact on this rare coralline algae is a compelling one, showing just how critical the issue is. 

Through projects such as Tor to Shore and Upstream Thinking, Cornwall Wildlife Trust has been working with fishers on sustainable management practises and with farmers to reduce agricultural run-off. However, this recent discovery highlights how vital this work is and how crucial our marine environment remains.