An era of expanding deep-ocean industrialization is before us,with policy makers establishing
governance frameworks for sustainable management of deep-sea resources whiles cientists learn more
about the ecological structure and functioning of the largest biome on the planet. Missing from
discussion of the stewardship of the deep ocean is ecological restoration. If existing activities in the
deep sea continue or are expanded and new deep-ocean industries are developed, there is need to
consider what is required to minimize or repair resulting damages to the deep-sea environment.
In addition, thought should be given as to how any past damage can be rectified. This paper develops the
discourse on deep-sea restoration and offers guidance on planning and implementing ecological
restoration projects for deep-sea ecosystems that are already, or are at threat of becoming, degraded,
damaged or destroyed. Two deep-sea restoration case studies or scenarios ared escribed (deep-sea stony
corals on the Darwin Mounds of fthe west coast of Scotland, deep-sea hydrothermal vents in Manus
Basin, Papua New Guinea) and are contrasted with on-going saltmarsh restoration in San Francisco Bay.
For these case studies, a set of socio-economic, ecological, and technological decision parameters that
might favor (or not) their restoration are examined. Costs for hypothetical restoration scenarios in the
deep sea are estimated and first indications suggest they may be two to three orders of magnitude
greater per hectare than costs for restoration efforts in shallow-water marine systems.
c2013 The Authors. Published by Elsevier Ltd. All rights reserved.