Skip to main content


The Wadden Sea ecosystem is characterised by a system of tidal flats and barrier islands with extensive salt marshes. The Wadden Sea Area accounts for 60% of all the tidal areas in Europe and North Africa and provides a habitat for a very rich and varied flora and fauna. In 2009, the Dutch and German Wadden Sea Area were  added to the UNESCO list of World Heritage Sites.

As a coherent system, the Wadden Sea is more than an accumulation of separate populations. The Wadden system is based on biological, biogeochemical, climatological, hydraulic, geological and geomorphological components and processes. Not only trophic interactions (eating and being eaten in the food web) are important, but also interactions that occur via the environment (e.g. mud content being affected by organisms). These require a multidisciplinary approach within the natural sciences.

The Wadden Sea is an open system. Important exchanges of water, nutrients, mud and organic matter take place between the rivers and the coastal sea. The open structure requires a conceptual approach to the Wadden Sea as a link in the continuum from land to sea and not as a self-contained or isolated unit.

The Wadden Sea is a dynamic system. On ecological timescales, radical changes can also be observed. Change happens under the influence of both local (e.g. human exploitation, construction) and global drivers (e.g. climate, invasion by exotic species).

The Wadden Sea as a value-rich system. Any discussion of natural values involves the 'paradox of conservation in a changing world'. Changes are bound to happen in the system, but viewed from the point of view of nature conservation, not every change is equally desirable. Within the shifting boundaries of what is ecologically feasible, policy will have to focus on facilitating the most ecologically desirable changes. 

Examples of knowledge gaps and research needs are:

  • better understanding of the processes on which the food web is based, by improved monitoring, modelling and focus on qualitative aspects; paleoecological reconstruction of these processes;
  • comparative research into other tidal flat systems;
  • research into non-trophic interactions, including relations between ecosystem engineers and sediment dynamics;
  • monitoring the effects of global change; and
  • considering how to preserve and develop natural values while the boundary conditions are changing.

The Ecology portfolio is held by dr. Katja Philippart.