©2005 British Ecological Society

1. Global-scale environmental degradation and its links with non-renewable fossil fuels have led to an increasing interest in generating electricity from renewable energy resources. Much of this interest centres on offshore renewable energy developments (ORED). The large scale of proposed ORED will add to the existing human pressures on coastal ecosystems, therefore any ecological costs and benefits must be determined. 2. The current pressures on coastal ecology set the context within which the potential impacts (both positive and negative) of offshore renewable energy generation are discussed. 3. The number of published peer-review articles relating to renewable energy has increased dramatically since 1991. Significantly, only a small proportion of these articles relate to environmental impacts and none considers coastal ecology. 4. Actual or potential environmental impact can occur during construction, operation and/or decommissioning of ORED. 5. Construction and decommissioning are likely to cause significant physical distur bance to the local environment. There are both short- and long-term implications for the local biological communities. The significance of any effects is likely to depend o