Natural systems of sea and land
The natural systems of the coast and of the sea are inextricably linked to each other. Coastal waters are a breeding ground for all kinds of fish species, and the coast and coastal waters, including the Wadden area, are a breeding ground for birds, while the sand and the dykes provide a habitat for dozens of species of bottom-dwellers and salt-tolerant plants.
We are now starting to understand how the biochemical and morphological processes are linked and how they influence and determine the qualities of the system. Offshore and onshore nature reserves are therefore also linked to each other. This is consistent with the criteria issuing from the application of the Bird- and Habitat Directive.
The policy for the coast is aimed at working with soft sea defences as much as possible so that wildlife can develop there. The same shift can be seen in the low-lying areas inland from the coastal strip, where the “fight” against the sea is starting to make way for life with the salt water and is being responded to by developing saline crops. Restoration of the transition areas between freshwater and salt water through intervention in the Haringvliet, and fish migration in the Afsluitdijk and elsewhere are contributing to the recovery of natural systems for species that need both freshwater and saltwater habitats.
Activities on land also determine the quality of the marine ecosystem. Vast improvements have been realised by tackling onshore and offshore sources of pollution and by treating wastewater. The Water Framework Directive is the instrument for an approach based on catchment areas. More recently, litter is an aspect that is now being paid the necessary attention. Upstream sources are an important part of the origins of marine waste, in addition to waste generated by activities at sea and waste generated on the coast by recreational users.