During the last decades eelgrass beds and mussel beds have disappeared from the Wadden Sea. This caused a large number of plant and animal species that depend on these banks to disappear or decrease significantly. Furthermore, most top predators (rays, sharks, porpoise, bottlenose) declined or even disappeared from the system, whereas water quality deteriorated (eutrophication, increasing turbidity caused by more silt).
More and more scientific studies emphasize the importance of "ecosystem engineers" in intertidal areas such as the Wadden Sea. Ecosystem engineers are organisms that not only respond to environmental conditions (such as sediment properties and hydrodynamics), but also strongly influence them by their presence. They create suitable living conditions for themselves as well as for other species. Thus they play a key role in retaining biodiversity and the natural functioning of ecosystems.
Restore musselbeds, increase diversity
The participants in the project Waddensleutels investigate whether restoring 'ecosystem engineers' — especially mussel beds — can restore the ecosystem to a more species-rich and complex food web, with herbivores, predators of herbivores, predators of these predators, and finally top predators. In an experiment to be carried out at a number of locations in the Wadden Sea, resaearchers attempt to restore mussel beds.
In addition, on the basis of stable isotopes, a set of process indicators are developed that can determine and evaluate the degree of recovery of the structure of the food web. This food web not only includes the open mudflats, but also the salt marshes; both habitat types are strongly functionally linked through sedimentation.
More information on www.waddensleutels.nl