1. Institute of Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg; Oldenburg Germany
2. School of Geographical and Earth Sciences; University of Glasgow; Glasgow UK
3. Administration of the Wadden Sea National Park of Schleswig-Holstein; Tönning Germany
4. Applied Plant Ecology, Biocentre Klein Flottbek, University of Hamburg; Hamburg Germany
5. Royal Netherlands Institute for Sea Research (NIOZ); Yerseke Netherlands