Eelgrass restoration in the Dutch Wadden Sea : methodology and first results

Before ca. 1930, Eelgrass (Zostera marina) was widespread throughout the whole of the Wadden Sea. Infrastructural works, disease, eutrophication and other factors have contributed to its demise. In the Dutch Wadden Sea Eelgrass has virtually disappeared. Within the European Water Framework Directive targets are set to increase its occurrence. With the reduction of nutrient runoff from land, the area of suitable habitat has increased. In Germany, Eelgrass has shown a remarkable recovery in the intertidal. In the Netherlands this has not been the case, even though models indicate that there is suitable habitat available. A hypothesis, that the lack of recovery is due to a lack of sufficient seed availability, is currently tested in a large-scale recovery project. The methodology is based on a technique developed in the U.S.A., where it has been successfully used, particularly on subtidal populations. The method was adapted to be used in the intertidal in the Wadden Sea. First results are encouraging, but there is no guarantee that the meadows are able to persist and increase. The various natural and anthropogenic changes in the system preclude the return to any historical reference situation. However, increasing the occurrence of a key species, characteristic for the Wadden Sea, may be possible.