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
Canvey Island along with the Benfleet Urban District in the Local Government Act 1972 to form the local government district and borough of Castle Point. Since the 2010 General Election, the Member of Parliament representing the parliamentary constituency of Castle Point has been Rebecca Harris of the Conservative Party. Canvey holds two seats on Essex County Council. , the seat of Canvey Island West is represented by Ray Howard of the Conservative Party, while Canvey Island East is taken by Brian Wood (replaced in May 2013 by Dave Blackwell) of the Canvey Island Independent Party. Canvey is represented on Castle Point Borough