Have you heard the term ‘blue carbon’ thrown around lately? It’s becoming an increasingly-used term by scientists, conservation groups and governments as more and more research reveals the power of our oceans in storing carbon. You’ve probably spotted it across social media, too!

But what is it, and why is it so important? Here’s everything you need to know – plus, exciting news about how Mounts Bay’s seagrass habitat has a unique role to play in tackling climate change.

So, what is ‘blue carbon’?

‘Blue carbon’ refers to the significant ability of marine habitats to absorb and store carbon dioxide, one of our biggest challenges when it comes to the current climate crisis. Typical examples include seagrass meadows, mangroves and salt marshes – the ‘big three’ – with these habitats storing substantial amounts of carbon in their plant material and sediments. In fact, research now indicates these blue carbon ecosystems store up to three to five times more carbon per hectare than land-based forests!

What’s more, they also provide vital habitats for thousands of marine species, playing an incredibly important role in supporting the biodiversity of our oceans.

As awareness around these blue ecosystems grows, we’re seeing more calls to protect what has now been dubbed ‘blue carbon’ storage areas, through schemes like Marine Protected Areas. However, despite its immense potential, the concept of blue carbon is still gaining recognition, especially at government level where decisive policy action is needed.

Cornwall’s blue carbon conservation

The good news is that Cornwall is already leading the way in marine conservation in the UK – unique in both its network of marine conservation community groups, its association of marine environmental bodies, and a local authority, Cornwall Council, who don’t mind getting their feet wet.

And, in Penzance, voluntary organisations like the Mounts Bay Marine Group are already taking an active role in working with fellow organisations (like Cornwall Council and Cornwall Wildlife Trust) to help the community learn more about what’s happening on the seafloor. In this case, mapping out the incredible seagrass meadows that thrive right here in Mounts Bay!

Mounts Bay: A seagrass haven in Cornwall

So, why is this seagrass meadow so exciting? In 2021, Cornwall Council commissioned a project to investigate seagrass in Mounts Bay, a particularly interesting blue carbon habitat that was known to exist in the area, to understand its true potential to help tackle the climate and ecological emergencies.

Although the presence of seagrass in the area was known, no one could have predicted its true scale. Using advanced survey methods, researchers found an area equivalent to 290 rugby pitches, and stretching for five kilometres, making it one of the largest seagrass beds in the UK and the second-largest in Cornwall (only surpassed by St Austell).

That’s important because seagrass beds not only help stabilise our climate but also improve water quality, protect shorelines, and support biodiversity. It only grows in seawater and provides a home and nursery for numerous marine species, including commercial fish, helping to support the livelihoods of many Cornish residents.

Threats to Mounts Bay’s seagrass beds

The survey also highlighted significant risks to these seagrass beds. Although part of Mounts Bay is designated as a Marine Conservation Zone, much of the seagrass bed lies outside this protected area, leaving it vulnerable to a number of impacts.

For example, activities like anchoring and mooring can damage seagrass meadows, impacting their growth and their ability to store carbon, while water quality issues and climate change pose substantial risks, too.

This is where community action can help protect these blue spaces, through both local and visitor information and education, while we continue to campaign for positive change at policy level.

Ongoing efforts to protect seagrass in Mounts Bay

Since the 2021 survey, Mounts Bay Marine Group has been leading hands-on conservation efforts, supported by local organisations such as the Cornwall Wildlife Trust. This summer, their citizen science programme trained community volunteers to snorkel and survey the seagrass beds, gathering valuable data while raising awareness locally.

Perhaps one of the most exciting aspects to come out of the survey was the discovery of a previously unmapped patch of seagrass near the Mount, building a better picture of how substantial this vital habitat really is.

Other work has also been underway with the Ocean Conservation Trust, a member of the Mounts Bay Seagrass Project working group, as they prepare to launch a new study using satellite technology. This innovative approach will monitor anchoring patterns across several sites in the southwest, including Mounts Bay, and will provide critical data on how recreational boating activities may impact these sensitive habitats.

Image: Clare Marshall

Meanwhile, the Cornwall Wildlife Trust, in partnership with the St Aubyn Estate, also created a beautiful film on seagrass which can be accessed via a QR code on a new interpretation board in Marazion (check it out, right here). It gives visitors a closer look at the underwater world of seagrass and the critical role it plays in local ecology.

Looking ahead for blue carbon in Cornwall 

Other surveys have revealed more seagrass beds around the Cornish coast, from St Austell to the Fal and Helford Estuaries, and, today, a small working group led by Cornwall Council has formed to build the Blue Action Project, which aims to understand the pressures on the seagrass by recreational activities such as anchoring and mooring. It’s also looking at how we can work as a community to both raise awareness of its value and protect this special area for future generations to enjoy.

For those interested in supporting blue carbon initiatives or learning more about the ongoing conservation efforts, reach out to Cornwall Council’s Blue Action Project team via Abigail.crosby@cornwall.gov.uk.

You can also keep up with the latest happening in Penzance and the surrounding area from Mounts Bay Marine Group, here.

Header image: Matt Slater