Offshore marine renewables energy developments (MREDs), particularly in the light of extensive offshore wind farm development in shallow shelf seas, are expected to affect the structure and functioning of marine ecosystems. Several activities linked to the installation and operation of MREDs each have their differential impacts onto the ecosystem. The benthos plays key roles in the ecosystem, supporting numerous ecosystem goods and services such as long-term carbon storage and food resources for higher trophic groups (e.g. fish, birds, mammals and including humans). Development of MREDs will initiate processes which are expected to affect benthic assemblages over various, currently unknown, spatial and temporal scales. This work provides a structured overview of ecological cause-effect relationships related to MREDs, based on a set of hypothesis-driven pathways supported by literature (>230 publications reviewed). Furthermore, this work evaluated the sensitivity of benthic causeeffect relationships to potential effects of MREDs on different spatial and temporal scales and weighted the assessment by confidence in existing knowledge and the consistency of effects among habitats. The outcomes allowed identification of knowledge gaps about ecological processes, in order to prioritize the ‘known-unknowns’ and highlight priority research areas. Our results suggest that the sensitivity of the benthos to MREDs is much higher than previously indicated, particularly where cascading effects lead to changes in ecological functioning. Filling existing knowledge gaps and understanding ecological processes and patterns occurring at low-trophic levels, including those within the benthos, are essential to maintain ecological integrity key to the ecosystem and to society even under MREDs developments.