Seagrass meadows return to Devon and Cornwall as South West Water backs restoration science

Beneath the waves off the South West coast, something remarkable is stirring. Once-declining seagrass meadows - lush, ribbon-like underwater fields - are showing strong signs of revival in the estuaries of Devon and Cornwall, raising hopes for marine biodiversity and climate resilience.

Now, South West Water is investing in a major research programme to better understand how its efforts to improve water quality may be helping this vital underwater habitat make a comeback, and what more can be done to support it.

The company has partnered with the University of Exeter’s Centre for Resilience in Environment, Water and Waste (CREWW), as well as seagrass experts from Plymouth Marine Laboratory and the Ocean Conservation Trust, to launch an in-depth investigation into the health of seagrass beds in key estuaries from the River Tamar to the River Exe.

“This work represents an important step in us better understanding the impacts of waste water on coastal marine habitats," said Dr Chris Laing, lead researcher from the University of Exeter. "Seagrass meadows are both critical habitats to protect and excellent indicators of marine health generally.”

Seagrass meadows, the only flowering plants that live entirely underwater, are critical to marine ecosystems. In the UK, two eelgrass species form the bulk of these meadows, which offer shelter for marine life, absorb carbon dioxide, and stabilise the seabed, helping prevent coastal erosion and storm damage.

Despite their ecological importance, seagrass habitats have suffered from decades of degradation, caused by physical disturbance and poor water quality from agricultural run-off and nutrients in treated wastewater.

But recent discoveries have revealed hope: some of the largest known seagrass beds in the UK are located in the estuaries and coasts of Devon and Cornwall. The revival appears to coincide with South West Water’s extensive infrastructure upgrades, part of a wider programme to reduce pollution and improve water clarity.

“Seagrass is one of nature’s quiet heroes,” said Carolyn Cadman, Director of Natural Resources and Net Zero at South West Water. “It helps clean our seas, stores carbon to help fight climate change and it shelters marine life. We’re so pleased to be working with experts at the University of Exeter and its partners to better understand how our work can help it recover and thrive.”

South West Water has invested heavily in wastewater treatment improvements along the South coast in recent years. The company’s Upstream Thinking catchment programme also partners with farmers to reduce nutrient pollution at the source, before it enters the rivers and estuaries where seagrass grows.

“Now, we’re seeing signs that nature is recovering,” said Mark Worsfold, Director of Asset Management at South West Water. “This investigation will help us understand how much of that seagrass recovery is linked to our efforts and crucially, what more we can do.”

The two-year research project will map seagrass health, link it to historical and recent improvements in water infrastructure, and explore future restoration options, such as planting new meadows and supporting ‘blue carbon’ initiatives where carbon locked in marine habitats can count toward climate goals.

The project will focus on collaboration, using the findings to inform decisions not only within South West Water but across the wider sector.

“This is all about understanding the science and building partnerships,” said Hannah Bailey, Biodiversity Action Officer at South West Water. “We want to use and share our data with others - other water companies, universities, conservation charities - to build a bigger picture of what works, and where.”

The initiative is part of South West Water’s broader Growing Nature to 2035 strategy, which commits to protecting high-value habitats, restoring degraded ecosystems, and working at the catchment level to support biodiversity.

Beyond carbon storage and water quality, seagrass beds are biodiversity hotspots. They provide refuge for an array of marine life, including seahorses, crabs, juvenile fish, and small sharks, making their protection vital to sustaining marine ecosystems in the South West.

The current investigation will help ensure that restoration and protection efforts are targeted, evidence-based, and backed by long-term investment.

If successful, it could also lay the groundwork for recognising seagrass as a carbon-offsetting resource under emerging blue carbon standards, connecting marine conservation directly to climate action.

In a region with a strong maritime identity and economy, the revival of these submerged meadows is not just an ecological success story, it’s a symbol of what happens when science, industry, and local communities work together to restore the balance of nature.