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Langstone Oysterbeds
The Langstone Oysterbeds saline lagoon is part of the West Hayling Local Nature Reserve on the north-west side of Hayling Island in Hampshire. It supports nationally important numbers of nesting little terns, Sterna albifrons, and is managed by Havant Borough Council.
This lagoon was created in 1997, when about 100,000 tonnes of rubble were removed. Approximately 30% of the lagoon's water is exchanged with the main harbour on each tide. This is too much to create the stable lagoon conditions required by specialist invertebrates.
Erosion affects the chalk embankments and the water exchange weirs. If one of the weirs were to fail, the lagoon would be lost. The high spring tides during the little tern breeding season resulted in flooding and loss of nests.
Actions to address threats
Three of the four tidal weirs have been in-filled to stabilise the water conditions in the lagoon to favour specialist species. The fourth weir is being reinforced to withstand the tidal pressure. This will also provide greater protection to the nesting island.
Three of the four tidal weirs have been in-filled to stabilise the water conditions in the lagoon to favour specialist species
The nesting island was raised using shingle, to prevent inundation on spring tides and to offset erosion.
Vegetation is cleared from the island annually to provide suitable nesting conditions for the little terns, which have responded by increasing in numbers.
Monitoring of biological change in the lagoon has continued throughout the project.
Volunteers do much of the work on the lagoon from the Friends of Langstone Harbour.