This 40-km long water-body was formerly an estuary of the Rhine/Maas river system, via Hollands Diep (025) and Lake Volkerak (026), but has been closed off from the sea since 1986 by a storm-surge barrier which allows the tidal regime to continue with some restrictions. The sea can be completely shut out during storms or high tides. Two freshwater lakes have developed on the eastern side following the construction of secondary dams (Markiezaat and Zoommeer, 029 and 030). South of this area, Lake Veersemeer (031) came into being following the closing of the Veerse Gat in 1961. This site, together with sites 029 and 030, formed part of a single, larger site (former site NL050) in the previous pan-European IBA inventory (Grimmett and Jones 1989).
This is the most important intertidal staging area for ducks and waders in south-west Netherlands. Thousands of geese Anser, feeding in adjacent farmland polders, use the area as roost. Recurvirostra avosetta and Charadrius alexandrinus breed in small lagoons (`inlagen', inland of the dyke) and at Neeltje Jans (building site of storm-surge barrier).
Pressure/threats to key biodiversity
The main problems are: the reduction of tidal volume and flow-speed by 30% due to the building of the storm-surge barrier; cockle Cardium fisheries and shellfish farming; disturbance by ultra-light aircraft and by the air force; and the expansion of recreation (boating). The SPA and Ramsar designations also include Markiezaat (030).
National Partial International High340 ha of IBA covered by Natural Monument (Oosterschelde-binnendijks, 340 ha). 240 ha of IBA covered by Natural Monument (Oosterschelde-binnendijks, 240 ha). 1,230 ha of IBA covered by Natural Monument (Oosterschelde-buitendijks, 1,230 ha). 22,000 ha of IBA covered by Natural Monument (Oosterschelde-buitendijks, 22,000 ha). 224 ha of IBA covered by Nature Reserve (Schelphoek, 224 ha). 149 ha of IBA covered by Nature Reserve (Thoolse Schorren en Slikken, 149 ha). 10 ha of IBA covered by Nature Reserve (Inlagen Anna Friso, 10 ha). 45 ha of IBA covered by Nature Reserve (Inlagen Noord-Beveland, 45 ha). 752 ha of IBA covered by Nature Reserve (Oosterschelde Buitendijks, 752 ha). 36,160 ha of IBA covered by Special Protection Area (Oosterschelde, 38,000 ha). 36,160 ha of IBA covered by Ramsar Site (Oosterschelde en Markiezaat, 38,000 ha).
BirdLife International (2022) Important Bird Areas factsheet: Oosterschelde. Downloaded from
http://www.birdlife.org on 22/01/2022.