Abundance of organisms during a field experiment in the Wadden Sea off the island of Sylt, Northern Germany

The ring experiment has shown that biogenic habitat change from resident mussel beds to novel oyster reefs does not constitute a threat to species diversity but causes a shift in abundance of dominant associated species. Mussels and oysters may be functionally equivalent as consumers. However, the epibenthic biogenic structures they generate seem unfold subtle differences in habitat properties. Their community effects can only be explained in the context of the ecological web of species interactions. The differences in infauna and epifauna on mussel, mixed and oyster belts will have implications on foraging birds as well as on the relative proportions between mussels and oysters in the intertidal Wadden Sea in the years to come.