Background The Zwin is the largest and most important tidal salt marsh site in Belgium, with a surface area of nearly 180 ha on Belgian territory – 125 ha of tidal saltwater lagoon, gullies and salt marshes and 55 ha of sand dunes and tidal sandy beach – and a further 27 ha in the Netherlands. It was defined as a “wetland of international importance for waterfowl” by the RAMSAR convention. In the western part of the site a lagoon was created by sand extraction in the 1950s. Here, small islands have for decades offered a safe breeding opportunity for numerous common tern (Sterna hirundo), black-headed gull (Larus ridibundus), avocet (Recurvirostra avosetta), redshank (Tringa totanus) and shellduck (Tadorna tadorna). Numerous species, included many listed in Annex I of the Birds Directive, also overwinter on the site. Since the 1980s, the Zwin has suffered a dramatic loss of biodiversity. Sand deposits have led to the gradual filling up of the lagoon, causing loss of safe breeding opportunities and sleeping sites for the birds, as the former islands are becoming connected to the mainland and accessible to ground predators. The deposited sand probably originates from the increased marine erosion of the sandy beach and fore-dunes, so that the loss of biodiversity can be considered an example of coastal squeeze as a consequence of climate change. This situation has also led to the loss of the habitat type ‘1140 Mudflats and sandflats not covered by seawater at low tide’. Finally, the overgrowth of willows and reeds, the development of fresh and brackish ponds and the accumulation of litter have led to the disappearance of the natterjack toad (Bufo calamita). Objectives The Flemish regional nature and forest agency, which became the manager of the Zwin in August 2006, is aiming to restore the rich biodiversity of this internationally important Natura 2000 site by carrying out large-scale restoration of the ecological dynamics in the Zwin area, thus enabling appropriate implementation on the Birds and Habitats Directives. Specific aims include: Restoration of the habitat types ‘2190 Humid duneslacks’ and aquatic biotope for the Natterjack toad by excavating six depressions in the contact-zones between fresh groundwater and brackish water; Restoration of salt-marsh with colinising Salicornia and other annuals on mud and sand to a more developed salt meadows (Glauco-Puccinellietalia maritimae) over 8 ha by cutting off Elymus athericus sods; Restoration of opportunities for nesting, foraging and resting for coastal bird species, safeguarded from terrestrial predators by restoring the tidal lagoon (9 ha) with its ‘bird-isles’ (3 ha); Repelling the encroachment of the salt marshes and dunes with high grasses, in order to restore intertidal habitat types 1330, 2120, 2130 and 2190. Livestock grazing will be introduced on 80 ha of salt meadows and 9 ha of dune habitats; and Improving the supply of salt seawater in the tidal floodplain by enlarging the tidal inlet through the fore-dunes, so improving dynamics in the tidal gullies and slowing down the deposit of sand. The project will also aim to raise public awareness and support for its measures through several communication actions. Expected Results: The restoration of the western controlled tidal lagoon in the Zwin floodplain over 12 ha will offer breeding foraging and resting opportunities for species included in Annex I of the Birds Directive; The restoration to an optimal condition of 59 ha of the habitat types 1140 (also resulting in foraging opportunities for wading birds), 1310 and 1330; The restoration of more than 30 ha of the habitat types 2120 (‘white dunes’), 2130 and 2190 by introducing grazing and cutting off sods; and The restoration of the habitat type 2190 and simultaneously the habitat for the natterjack toad on 0.5 ha, scattered over six locations in the dunes and the transition zones between dunes and salt marshes.It is expected that enlarging the main tidal gully and its mouth to the sea will increase the tidal currents, especially at ebb tide and slow down the sedimentation process.