UK’s largest oyster reef restoration milestone reached as 260 volunteers prepared 20,000 oysters for the Solent

The University of Portsmouth last week welcomed hundreds of volunteers to its Institute of Marine Sciences (IMS) to help prepare 20,000 native oysters for deployment onto a new reef in Chichester Harbour - marking a major milestone in the UK’s largest subtidal oyster reef restoration project.

Between 11–15 May, around 260 volunteers gathered in Portsmouth for a series of “biosecurity days”, carefully cleaning and checking oysters before their release onto the newly constructed reef. The oysters were deployed in Chichester Harbour by Blue Marine Foundation at the end of the week, representing a significant step in restoring one of the Solent’s most threatened marine habitats. 

The work forms part of the Solent Seascape Project, a marine restoration initiative led by ocean conservation charity Blue Marine Foundation in partnership with Chichester Harbour Conservancy and the University of Portsmouth’s Institute of Marine Sciences. The project is supported by the seabed owner, the Manor of Bosham. 

Native oyster populations in the Solent have declined by around 96 per cent over the past century, driven by overfishing, disease, invasive species and declining water quality. Yet oysters remain one of the marine environment’s most important “ecosystem engineers”: a single oyster can filter up to 200 litres of water a day, while oyster reefs provide habitat for hundreds of marine species and help protect coastlines from erosion. 

Last month, teams completed the placement of “cultch” - the shell and stone material that forms the base of the reef. The newly cleaned oysters were then added to this habitat to begin establishing a thriving native population in the harbour. 

For centuries, oysters were central to life across the Solent, with harvesting in Chichester Harbour dating back to Roman Britain. The restoration aims not only to rebuild biodiversity, but to reconnect coastal communities with a vital part of their maritime heritage. 

Volunteers played a crucial role in the project, scrubbing and washing oysters to remove invasive species and pathogens before deployment. The large turnout marked the biggest volunteer effort the initiative has seen so far. 

Professor Jo Preston, lead researcher at the University of Portsmouth’s Institute of Marine Sciences, said “It was incredibly inspiring to see so many people come together to help restore a species that once defined our coastal heritage. Native oysters are powerful ecosystem engineers, and this deployment represents a major step towards rebuilding a healthier, more resilient Solent. The enthusiasm of our volunteers shows how strongly communities want to be part of protecting and restoring our seas.” 

Dr Luke Helmer from the Solent Seascape Project added that the deployment represented a significant moment for marine restoration in the UK, while Ashley Hatton of the Manor of Bosham welcomed the project and confirmed the site will be monitored over the next five years to track its success. 

The oyster reef forms part of the Solent Seascape Project, the UK’s first large-scale seascape restoration initiative, which is working to restore and reconnect habitats including seagrass meadows, saltmarsh, seabird nesting sites and oyster reefs across the region. 

The project is supported by East Head Impact and the Endangered Landscapes & Seascapes Programme (ELSP), managed by the Cambridge Conservation Initiative and funded by Arcadia, with additional support for the reef provided by the Environment Agency.