South Thames Estuary and Marshes 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 Wild Birds. Over 20,000 waterfowl use this site, and some species are present in internationally important numbers. There
Tamar–Tavy Estuary Seaweeds, green algae and communities of polychaete worms are all found in the estuary system; near Calstock is found the shrimp "Palaemon longirostris", which has been recorded in only two other estuaries in Britain. The estuary is also one of only two sites in the UK where the fish, allis shad, spawn. Other larger animals found in undisturbed parts of the SSSI include the European otter, the common kingfisher and dormice. Tamar–Tavy Estuary The Tamar–Tavy Estuary is a Site of Special Scientific Interest (SSSI) covering the tidal estuaries of the River Tamar and the River Tavy on the border between