Researchers are exploring how nature-based approaches could be used to improve water quality and marine environments in coastal areas of the English Channel

Coastal intertidal waters have national importance for breeding birds, plants and invertebrates. The rich and varied habitats in the Solent and Poole harbours provide great conditions for breeding birds, such as terns. They are also home to a vulnerable ecosystem of seagrass meadows, as well as saltmarshes and invertebrates, which are vital to all life and make up more than 50 per cent of all known species.

A critical environmental challenge to these areas is increased nutrient levels in coastal waters caused by fertilisers, and wastewater and sewage discharge. These additional inputs have resulted in the excessive growth of algae (known as eutrophication) on intertidal mudflats, saltmarshes and seagrass meadows covering thousands of hectares. The result is ecological impacts, as well as economic and human health issues.

The RaNTrans (Rapid reduction of Nutrients in Transitional Waters) project is the first of its kind to use the natural processes of native oysters, seaweed and marine worms to deliver sustainable solutions that will rapidly reduce algal mat coverage and contribute to reductions in nutrient levels on both sides of the Channel.

The team demonstrating how oysters are used to filter the water in The Solent

These include:

  • Feeding algal mats to polychaete worms and converting these to aquaculture feed
  • Establishing and optimising oyster aquaculture as native European oysters (Ostrea edulis) filter the water, reducing nutrient levels and ultimately algal mat growth in addition to increasing biodiversity, as oyster colonies support thousands of other marine species
  • Innovative uses of algal mats by extracting chemicals with human health benefits

The project comprises nine partners from across the UK and France, led by the University of Portsmouth. Project partners are testing these techniques at four sites – two in France (Baie des Veys, Calvados; and Ledano Mudflat, Côtes d’Armor) and two in the UK at Langstone Harbour and at Poole Harbour.

The Solent’s environment is under increasing pressure and more must be done to turn the tide and enable nature recovery

Professor Gordon Watson, School of Biological Sciences, University of Portsmouth

Professor Gordon Watson, from the University of Portsmouth and RaNTrans project leader, said: “The Solent’s intertidal areas support a vast and important diversity of wildlife and are a key asset for the region. Despite this, the Solent’s environment is under increasing pressure and more must be done to turn the tide and enable nature recovery.

“With the results of this project, we hope to be at the forefront of further research into the reduction of nutrients around our coastlines. By sharing our research with Natural England, we hope to create a strong collaboration which aligns both scientific research and changes to policy using nature-based solutions to help restore water quality for the benefits of wildlife, businesses and communities in the Solent region.”

Allison Potts, Natural England’s Thames Solent Area Manager, said: “We’re really pleased to be working with the University of Portsmouth and other partners to deliver this project. Poor water quality in the Solent is a significant environmental issue and we are very keen to be exploring ways to make our water cleaner.

“Not only is this good for the Solent’s important wildlife, but also because it is such an important place for the people who live, work, and recreate here too. The many facets of our work will see cleaner and safer water by the restoration of native oysters’ populations, which also restores habitat for many fish species.”

By developing the business potential of these sustainably-produced outputs, the project will also show how biodiversity preservation and environmental improvements can underpin regional job creation as oysters, aquaculture feeds and seaweeds are multibillion-dollar industries. These emerging trends will significantly impact the outlook of the marine industry in coming years.

Restoring nature and harnessing its power as the solution to the urgent problems we face is absolutely vital if we are to tackle climate change, biodiversity decline and water pollution

Marian Spain, Chief Executive of Natural England

Marian Spain, Chief Executive of Natural England, added: “Natural England is proud to be a part of the RaNTrans project, working with organisations on both sides of the channel to remove the damaging algae that grows as a result of pollution of these delicate marine ecosystems.

“Restoring nature and harnessing its power as the solution to the urgent problems we face is absolutely vital if we are to tackle climate change, biodiversity decline and water pollution.

“No one organisation, or country, can do what’s necessary on its own, but each can bring its own specialist expertise, experience and evidence to the partnership and start to turn targets and ambitions into practical action on ground.”

The three-year project, which is funded by the European Regional Development Fund through the Interreg France (Channel Manche) England Programme, is halfway through and will finish in June 2023.

“It’s great to see this joint working to deliver for the environment”, said David Hill, Director-General for Environment, Rural and Marine at Defra.

“Improving our landscapes and seas, providing cleaner water, protecting species, and restoring habitats alongside supporting greener farming and fisheries. Sustainable development has never been more important for Defra.”

We will be holding a workshop at the University of Portsmouth on the 3rd November 2022.

Please register your interest to attend this event. We plan on sharing project findings and having exciting discussions on the next steps for nutrient remediation in the Solent and further afield.

Eventbrite registration here

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