Summary & Outcomes
In December 2014, the RSPB purchased 28ha of disused clay quarry which Wild Purbeck had assisted in turning into a saline lagoon with associated heathland and ancient woodland habitat. The site fronts the shore of Poole Harbour and is situated at the north-east corner of RSPB Arne reserve. Saline lagoons are rare in England, and the acquisition will secure the long term future of this site.
As part of the project, Bournemouth University carried out a hydrological study of the site, recording tidal exchange volumes and salinity levels. Ecological monitoring has also been undertaken to record the establishment of species within the lagoon. This showed that the biomass of animals recorded in the sampled water columns compared favourably with those recorded in the lagoon at Brownsea.
The site includes saltmarsh, undisturbed beach with increasing roosts of oystercatcher and Shelduck with 5ha ancient woodland containing lichens and notable invertebrates, 7ha SPA/SAC heathland with breeding nightjar and a suite of butterfly and moth species including the BAP Priority Goat moth.
Highlights and challenges
The site is a former ball clay quarry owned by Imerys. The RSPB has worked with Imerys and Dorset County Council to complete its restoration and optimise its value as a nature reserve. RSPB has the first opportunity to purchase the site at market value – this was higher than originally anticipated due to the associated sporting rights. By securing a grant from Viridor Credits and match funding from the WPNIA, the RSPB was able to secure the purchase and long term future of the site.
The monitoring and research already begun will be continued, and it is hoped the site will become more important for birds in the future, as well as supporting larger invertebrate populations for wading birds to feed on. Given the vulnerability of the Brownsea Island lagoon to sea level rise, the Arne saline lagoon could also become an important part of the climate change adaptation and planning strategy for Poole Harbour. It is also planned to use the site as a minerals restoration demonstration site.