Ecological best practice in decommissioning: a review of scientific research.

Abstract

The Oslo and Paris Commissions (OSPAR) decision 98/3 prohibits the dumping of man-made structures (MMS) offshore. However, there are regions of the world where MMS are recognized as providing an ecological and societal benefit through the provision of ecosystem goods and services. This review provides a commentary on our current understanding of the ecological influence of man-made structures, the consequences of their decommissioning and recognizes that our knowledge is far from complete. It is known that a diverse and complex ecosystem of attached organisms develops on submerged structures which supports a localized food web that could not exist without them. However, our lack of detailed information makes modelling of system response to decommissioning very tentative. Ideally, we should use the best possible scientific information to reach a consensus as to whether the blanket removal of MMS (excepting derogations) is the most environmentally supportable option. The evidence available to-date shows both benefits and some risk in leaving MMS in place and this needs to be examined without preconception. On the UKCS, MMS as artificial habitats are not considered under the Habitats Directive, irrespective of the value or rarity of the species present. We conclude that a more comprehensive regulatory process, together with the recognition of the ecology associated with man-made structures, would allow science to play a role in the decision-making rather than supporting a blanket policy ignoring ecological context.