Oysters reintroduced into Solent to boost biodiversity and improve water quality

European flat oysters are being reintroduced to the Solent to boost biodiversity and improve water quality.

The joint Ministry of Defence (MOD) and charity conservation project will release 2,000 oysters into the strait between the Isle of Wight and the Hampshire coast.

Conservationists hope they will encourage marine life back and help to clean the heavily-used waters, which has 130,000 movements from vessels around Portsmouth Harbour each year, including the Royal Navy.

Several oyster crates have been installed by the project team on pontoons at the southern end of Whale Island in Portsmouth to grow juvenile oysters.

The nearby waters are used daily by cross-Channel ferries, merchant vessels visiting the commercial port, and warships operating from Portsmouth Naval Base.

Once fully grown, after about 18 months, they will be released into two reefs – one in Hamble and one in Langstone.

The bid to re-establish a healthy population of the native species comes as few remain in the Solent, once the largest fishery in Europe for the flat Ostrea edulis oysters.

The species was replaced by the invasive Pacific oyster, which potentially has detrimental consequences to the local marine environment.

Harriet Rushton, a marine biologist who established and managed the project, said: “These oysters are being grown for conservation, re-introducing a lost native keystone species in the Solent, which will enhance biodiversity and help clean the water.

“This shows the Ministry of Defence’s commitment to improving the UK’s ecosystem and helping to address climate change, thus contributing to minimising climate and ecosystem pressures on MoD training and operations.”

Defence minister Luke Pollard said: “The Royal Navy has proudly used the Solent for centuries and is dedicated to supporting the local area, including finding ways to offset collective environmental impacts.

“This is a brilliant initiative and the partnership between the Royal Navy and partners shows that through collaboration we can improve the marine environment and strengthen biodiversity, to the benefit of our forces too.”

A healthy and diverse population of oysters can benefit UK waters by filtering the seas, forming reefs and removing carbon from the environment.

A single adult oyster can filter up to 200 litres of water a day, removing chemicals and pollutants, the MoD said.

Once released and settled, the oysters merge into one another to form reefs that provide shelter and food for marine life.

The species extracts carbon from seawater to build their shells, which become buried in sediment when they die and transform into solid beds of limestone, removing more carbon from the atmosphere.

Rod Jones, the Royal Navy’s senior maritime environmental protection adviser, said there is potential for the initiative to be rolled out beyond the Solent if it is successful.

“If we can grow oysters here, which is far from an ideal environment as it’s a very industrial setting,  then there are clearly opportunities to grow them elsewhere, other naval bases or MoD sites,” he said.

“The Navy has been operating in the Solent for centuries so it is only right that we should be involved in protecting its environment.”

The initiative, known as the Whale Island Native Oyster Restoration Project, is a collaboration between the Salvage and Marine Operations (Salmo) Wrecks team – part of the MOD’s Defence Equipment and Support organisation – the Royal Navy, the Defence Infrastructure Organisation (DIO) and the Blue Marine Foundation (BMF) charity.

It has been supported by £6,000 of funding from the DIO’s Conservation Stewardship Fund.