The Oosterschelde Estuary : A Case Study of a Changing Ecosystem

The Oosterschelde project is technically and scientifically unique. The building of the storm-surge barrier, together with the two secondary dams, represents an important breakthrough in marine civil engineering. The project offered ample opportunities for integrated physical, chemical, geological and biological research. Integration of the knowledge gained raised the entire project to the level of a case-study of a changing estuarine ecosystem, and demonstrated the effects of human interference in a non-polluted estuary. The main argument for building the storm-surge barrier was storm-flood protection, combined with conservation of the outstanding values of landscape and nature, fisheries included. The estuary is recognized as an international wetland, including sand- and mud-flats, feeding large numbers of migratory waterfowl, and further comprising deep tidal gullies, artificial rocky shores, salt marshes and inland brackish localities with specific aquatic plants and animals. The interest in storm-flood protection has recently gained momentum, owing to the wide international discussion on the impact of sea-level rise on society. Estuarine areas, the Oosterschelde included, are vulnerable to effects of sea-level rise. Considering the size of the project and the employment of a considerable number of cooperating scientists, an impressive document came into existence. The papers contain useful information for both scientists and managers involved in comparable projects, dealing with major environmental changes in estuaries. Notwithstanding the considerable physical and hydrochemical changes, the carrying capacity of Oosterschelde estuary has been maintained, with regard to the main functions of the ecosystem, viz. a valuable, protected tidal wetland, high quality shellfish cultivation and local fisheries and extensive water-recreation.