New reef created for 30,000 oysters in the Solent

Posted: 13th April 2023

Photo: Blue Marine Foundation

Foundations for the largest restoration reef in the Solent were laid as part of the Solent Seascape Project – a multi-million dollar initiative to restore marine habitats across the Solent region in southern England. The Solent Seascape Project is part of the new cohort of seven landscape and seascape restoration projects funded by the Endangered Landscapes Programme. 

Working closely with the River Hamble Harbour Authority and local contractors Jenkins Marine, ocean conservation charity Blue Marine Foundation laid a thin veneer of shingle mixed with cockleshells, known as ‘cultch,’ covering 2,500 metres square onto the seabed.

Oysters sourced from south Wales will be transferred to the site to seed the area at the Swanwick bend in the River Hamble in a few weeks, after passing through a strict biosecurity process where they are cleaned, measured and checked.

As well as oyster reefs, the Solent Seascape Project will work to restore saltmarshes, seagrass meadows, and seabird nesting habitats. Photo: Blue Marine Foundation.

The Solent was once the largest and most important oyster fishery in Europe, but over the last decade oysters have significantly decreased in numbers as a result of poor water quality, competition from invasive species, disease and fishing pressure. The loss of the native European oyster not only negatively impacts the livelihoods of local fishermen, but also removes the many ecosystem services that a healthy oyster population provides. Adult oysters can filter as much as 200 litres of seawater each day, improving water clarity and removing excess nutrients. Oysters also stabilise marine sediments and dramatically increase biodiversity, including commercially important fish species.

Louise MacCallum, Solent Project Manager for Blue Marine Foundation says: “This new restoration reef has taken more than a year to plan. The River Hamble is one of the busiest waterways in the UK. As well as creating a perfect home for 30,000 oysters, it has also been critically important to ensure that our operations do not affect navigational safety for the many people who enjoy boating and water sports on the river.”

Oysters provide a range of ecosystem services including water filtration and sediment stabilisation. Photo: Blue Marine Foundation.

In the coming years scientists from Blue Marine, the University of Portsmouth and the University of Southampton will monitor the new reef. Oyster survivorship and biodiversity gains will be measured and compared to another part of the river where no restoration activity is taking place.

In 2021 the Solent Seascape Project team restored a 1,000 square metre oyster reef in Langstone Harbour. The Langstone reef has already attracted a wealth of marine fauna including cuttlefish, catsharks and even seahorses. To date, this existing reef and the new reef in the River Hamble are the only restored reefs in the Solent region.

The new reef will scale up the success of the restoration reef in Langstone Harbour created in 2021. Photo: Blue Marine Foundation.

Joanne Preston, Reader in Marine Ecology and Evolution at the University of Portsmouth says: “This reef deployment is another significant step forward in re-creating the subtidal oyster reef habitat that has been all but lost in the Solent and across Europe. We hope this reef creates a tipping point;
kick-starting a population of native oysters that builds over several generations and provides offspring that will spill over and populate other areas. We also predict strong biodiversity gains and water quality improvements, which we will be monitoring over the next five years.”

Marine habitat restoration is in its infancy in the UK. As well as restoring oyster habitats, the Solent Seascape Project team will be restoring seagrass meadows, seabird nesting habitat and salt marsh across the Solent region. As the project progresses the team hopes to use the lessons learned to create a blueprint for restoring temperate marine habitats elsewhere in the UK, and beyond.

To find out more about the Solent Seascape Project, visit their project page

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