Coastal areas worldwide are under high utilization pressure and are additionally threatened by climate change (storms, high temperatures, lack of oxygen). This leads to strong changes of the entire habitat including the metabolism. Therefore, a comprehensive and in-depth understanding of microbial processes is urgently needed, especially in shallow waters. However, investigations in shallow waters are extremely difficult due to the high dynamics and strong wave impact and require close cooperation across disciplinary boundaries which is to be realized within the framework of a long-term initiative at the IOW. How microbial processes of the nitrogen cycle are influenced by water-sediment interactions, or benthic colonization, will be investigated in this project. Rate measurements in the field, use of landers and laboratory experiments are planned. The goal is to quantify microbial processes and their interaction with near-bottom currents to better understand the coastal filter.