This spring, Blue Marine Foundation, supported by the University of Portsmouth’s Institute of Marine Sciences and over 140 volunteers, extended the native oyster reef in the River Hamble – a key milestone in the Solent Seascape Project’s aim to restore four hectares of oyster habitat.
Building the reef
Adding to the work carried out in 2023, a further 0.25 hectares were created using 278 tonnes of shell and gravel “cultch” material. This creates a substrate suitable for the oysters and provides a home for them to settle on.
Then over three days in May, more than 140 volunteers helped to scrub, clean, measure, weigh and tag 10,545 oysters at the Institute of Marine Sciences. This was to ensure that nothing additional was introduced in to the environment, other than the oysters.
Finally, the oysters were transported to the River Hamble and dropped on to the new reef below.
Why oyster reefs matter
Oysters (Ostrea edulis) are ecosystem engineers, creating habitats that support hundreds of marine species. A single oyster can filter up to 200 litres of water each day, helping improve water quality, while oyster reefs act as a natural buffer against coastal erosion.
Once abundant in the Solent, native oyster populations have declined by 95%, with serious consequences for biodiversity and water quality. By restoring reefs, Blue Marine Foundation and partners aim to bring back these benefits for people and nature.
Restoration at scale
Since 2017, Blue Marine Foundation and the University of Portsmouth have been working together to restore and protect oyster reefs in the Solent. Alongside reef creation, mature “brood stock” oysters are being placed in cages hung from pontoons, releasing millions of larvae into the water. These cages have already been found to shelter 97 other species, including the critically endangered European eel, juvenile spiny seahorses and sea bass.
The work on the River Hamble is part of the Solent Seascape Project, which is restoring key habitats across 52,200 hectares of one of the UK’s most heavily used waterways. By reconnecting habitats including saltmarsh, seagrass and oyster reefs, the project is helping to recover biodiversity, strengthen coastal defences and enhance carbon storage.
Looking ahead
The extension of the Hamble reef is a step toward the recovery of a once-thriving ecosystem. With continued restoration, oyster reefs across the Solent will again provide a foundation for marine biodiversity and a healthier, more resilient seascape.
To find out more about the Solent Seascape, visit their project page. This article was originally published on the Solent Seascape Project website.
