In many European countries offshore windfarm projects are accompanied by obligatory
environmental impact assessments, including baseline monitoring of the marine benthos and
demersal fish. The effects of offshore windfarm developments on the benthic system are complex.
However, legal baseline monitoring merely allows for net effect descriptions but not for identifying
and understanding the underlying processes. Instead, key processes should be identified and
become subject to hypotheses‐based target monitoring and/or experimental studies in order to
make environmental impact assessments more efficient and reduce duplication internationally. We
compiled an overview over the anthropogenic activities associated with the construction and
operation of offshore windfarms and identified cause–effect relationship to facilitate the
development of specific hypotheses. We expect offshore windfarming activities to modify the geomorphological
and hydrodynamic environment at different temporal and spatial scales. The
environmental effects will have consequences for the behaviour and physiology of benthic
organisms, including demersal fish, restructuring natural local populations and communities.
Major effects on biological production, biogeochemical processes, as well as on structure and
function related to biodiversity, are expected from the massive colonization of the artificial
underwater constructions by a specific hard‐bottom fauna which is naturally missing in soft
sedimentary habitats. Understanding the mechanisms behind these changes is a priority for
assessing and predicting the ecological implications for the benthic system. Such predictions may
help to develop science‐based mitigation actions