South Thames Estuary and Marshes are nationally scarce plants on dykes, and the diverse invertebra include nationally rare beetles, flies and true bugs. South Thames Estuary and Marshes South Thames Estuary and Marshes is a biological Site of Special Scientific Interest which stretches between Gravesend and the mouth of the River Medway in Kent. Part of it is a Nature Conservation Review site, Grade I, and part is a Royal Society for the Protection of Birds nature reserve. It is part of the Thames Estuary and Marshes Ramsar internationally important wetland site and Special Protection Area under the European Union Directive on the Conservation of
Dee Estuary channel which it cut through the base of the Wirral Peninsula. The estuary is a major wildlife area and one of the most important estuaries in Britain, amongst the most important in Europe for its populations of waders and wildfowl. The Environment Agency is the Conservation Authority, and the estuary is protected or listed under several schemes: Large parts of the area are within the RSPB's Dee Estuary Nature Reserve. The estuary supports some important natural fisheries, including salmon and trout on their way to and from the freshwater river, as well as sea-fisheries and shell-fisheries, especially cockles. From earliest