The workshop aimed at bringing experts working in the field of offshore wind farms – benthos together for the first time in order to get an overview on the state of the art. This was achieved by an extended poster session. The second issue of WKEOMB was to identify knowledge gaps and evaluating monitoring strategies. This issue was evaluated by disentangling the cause-effect relationships affected by the pressures of the activities during the construction and operation phase of offshore wind farms. All cause-effect relationships were summarized in a schematic presentation. The identifi-cation and a comprehensive overview of cause-effect relationships is a prerequisite for an efficient, hypothesis driven approach towards the disentanglement of the vari-ous effects of offshore wind farms on the marine benthos as well as on the whole eco-system. Further, manifold cause-effect relationships were prioritized based on three main research themes, biological resources – biogeochemical reactions – biodiversity, disentangled by the participants as relevant. An important outcome of the workshop is that benthos receives by far too little atten-tion compared to other ecosystem components (e.g. seabirds, marine mammals), al-though it contributes to a great extent to marine ecosystem services and goods, e.g. biodiversity, long-term carbon storage and trophic supply for higher trophic-level species. A second main outcome of WKEOMB was that legal baseline monitoring merely allows for net-effect descriptions but not for identifying and understanding the underlying processes. Key processes should be, thus, identified and become sub-ject to hypotheses-based target monitoring and/or experimental studies.