More than 15m juvenile oysters are to be released into the North Sea in one of the biggest rewilding projects in UK waters.

The scheme, which will use a unique rearing process, hopes to re-establish a huge oyster bed around Orkney that experts say will create a “trophic cascade” of climate and ecological benefits.

Richard Land, the marine expert leading the project, said it would have a knock-on impact on the entire ecosystem. “It won’t just benefit fish and the bay, it will benefit sea mammals, seabirds and the whole environment.”

Experts hope the scheme, which is being run by the Green Britain Foundation, the Nature Restoration Fund, Marine Fund Scotland and North Bay Innovations, will provide a template to revive oyster beds in coastal areas around the UK. “This project is a blueprint for a wider plan to reintroduce oysters to the UK and to European waters,” Land said.

Oyster beds used to be a key part of the UK’s marine ecosystems, covering huge areas of coast – some in the North Sea covered an area the size of Wales. But during the Industrial Revolution, oysters became a popular food source for UK workers – between 1840 and 1850, Londoners alone are estimated to have consumed 700m of the shellfish.

This overfishing, combined with increased pollution, climate change and deliberate removal to clear channels for shipping, has had a devastating impact on oyster populations and interdependent subspecies, triggering what scientists describe as a “negative cascade” that has decimated marine ecosystems.

However, experts believe restoration projects such as the one near Orkney offer the chance to rebuild thriving coastal waters – as well as helping to tackle the climate crisis and improving water quality.

Dale Vince, the founder of the Green Britain Foundation and one of the backers of the scheme, said research suggests oyster reefs can sequester significant amounts of planet-heating CO2. He said this project could see the restoration of about 15m oysters in a new bed covering more than 100 hectares (247 acres) – potentially sequestering up to 76 tonnes of CO2 each year.

But those behind the scheme said the real goal was to stimulate the natural spawning of beds, which once established around coastlines could dwarf that figure for carbon capture “by over a 1,000-fold per annum after about 15 years”.

Vince added: “This whole project actually came from: how do we get nature to do the carbon capture for us? Restoring native oyster beds is a perfect example of how we can work to restore nature and fight the climate crisis at the same time … By reintroducing them, we’re breathing life back into marine ecosystems – creating vital habitats for other marine life and reducing carbon in the atmosphere. It’s a perfect combination.”

The Orkney initiative cultivates juvenile oysters onshore on “plates” enriched with calcium carbonate. Once the oysters are established, these plates are put out into the sea on long lines that help them evade predators until they are big enough to survive and form beds, creating reefs made up of dozens of other species including scallops, molluscs, algae, seaweeds and invertebrates.

Alistair Carmichael, the Liberal Democrat MP for Orkney and Shetland, welcomed the plan. “Efforts to restore and recover historic wildlife in the isles are absolutely welcome,” he said, “particularly if there is an opportunity for carbon sequestration at the same time.

“Orkney has a long and productive history of working the seas that surround us. It is in all our interests to balance the needs and demands on our waters and our seabed so that everyone can benefit from it for generations to come.”

Philine Zu Ermgassen, from the University of Edinburgh, said reintroduction schemes were critical to restore oyster populations.

“As oysters are now so few in number, they are unable to recover in many locations without human intervention. It is exciting that hatchery techniques are developing to meet the needs of the growing restoration community. This innovation is key to producing enough oysters from local genetic stocks to support restoration and recovery of this hugely valuable ecosystem.”