More than 260 volunteers gathered in Portsmouth last week (11–15 May) to help prepare 20,000 native oysters for deployment onto a newly built reef in Chichester Harbour, as part of the UK’s largest subtidal oyster reef restoration project.
The large-scale effort forms part of the Solent Seascape Project, which is working to restore some of the Solent’s most threatened coastal habitats, including oyster reefs, seagrass meadows and saltmarsh. The oyster restoration work is led by ocean conservation charity Blue Marine Foundation alongside Chichester Harbour Conservancy and the University of Portsmouth’s Institute of Marine Sciences, with support from the seabed owner, the Manor of Bosham.
Volunteers took part in “biosecurity days” at the University of Portsmouth’s Institute of Marine Sciences, where oysters were cleaned and carefully checked before deployment onto the reef. Around 260 volunteers took part across the week, making it the initiative’s largest volunteer turnout so far.
Image: Kate L’Amie.
Bringing back native oyster reefs
The final deployment of oysters onto the reef took place in Chichester Harbour on Friday, 15 May, marking a major milestone in efforts to restore a species that has declined dramatically in UK waters.
For centuries, native oysters were part of everyday life across the Solent. Coastal communities relied on oyster beds for food, trade and employment, with evidence of oysters being harvested in the harbour dating back to Roman Britain. The restoration aims not only to recover a severely depleted species, but also to reconnect the region with an important part of its maritime heritage.
Native oyster populations in the Solent have declined by around 96% over the past century due to overfishing, disease, invasive species and declining water quality. Despite this decline, 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, helping improve water quality, while oyster reefs also create habitats for hundreds of marine species and help protect coastlines from erosion.
Image: Kate L’Amie.
Laying the foundations
Last month, project teams completed the placement of “cultch”, the shell and stone material that forms the base structure of the reef. The cleaned oysters were then added to this new habitat to help establish a thriving native oyster population in the harbour.
Dr Luke Helmer, from the Solent Seascape Project, said:
“This is a hugely significant moment for marine restoration in the UK. Native oysters were once abundant across the Solent, but populations have collapsed over the last century. By restoring oyster reefs at this scale, we’re helping rebuild an ecosystem that supports biodiversity, improves water quality and benefits coastal communities.”
“What’s especially exciting is the scale of public support behind this effort. Having hundreds of volunteers directly involved in preparing oysters for deployment shows how strongly people want to be part of restoring our seas.”
Image: Kate L’Amie.
Ashley Hatton from the Manor of Bosham said:
“The Manor of Bosham estate is delighted to support this environmental project, by providing the requested site in Chichester Harbour. We very much hope that the reintroduction of the native oyster species on this underwater reef will establish and thrive. Monitoring of the site, over the next five years, will determine the level of success.”
Volunteers taking part in the biosecurity days helped scrub and wash oysters to remove invasive species and pathogens before deployment onto the reef. The process was designed to give the reef the best possible chance of establishing successfully.
The restoration work forms part of the Solent Seascape Project, the UK’s first large-scale seascape restoration initiative. The project brings together multiple organisations to restore and reconnect habitats across the Solent, including seagrass meadows, saltmarsh, seabird nesting sites and oyster reefs.
This article was originally published on the Solent Seascape Project website. The Solent Seascape Project is supported by the Endangered Landscapes & Seascapes Programme, managed by the Cambridge Conservation Initiative and funded by Arcadia, alongside support from East Head Impact and the Environment Agency for the reef restoration work.
