The fate of Zostera marina as part of beach wrack at the Baltic Sea coast in Poel, Germany

Beach wrack plays an important role as an ecosystem engineer with its function to beach fauna in and off the water and its role to dune formation and preventing coastal erosion at land.The seasonality and species composition of beach wrack at the micro-tidal coast of the Baltic Sea was evaluated at the island of Poel and litterbag experiments were conducted, both at land and in the water column of the shallow coast. Special interest was given to the seasonal decay of seagrass of the species Zostera marina in the water until its complete disintegration. The decomposition experiments were divided into a light group in translucent mesh bags, and a dark group in black mesh bags: The influence of abiotic parameters on the microbial community during decay was the objective of these experiments.The results provide an important insight into the decomposition processes of seagrass at a micro-tidal coast, its lasting effects on beach management processes at recreational beaches and coasts and also into a balanced co-existence between humanity and nature.