Can the benefits of physical seabed restoration justify the costs? An assessment of a disused aggregate extraction site off the Thames Estuary, UK

• Published in: Marine pollution bulletin 2013-10, Vol.75 (1-2), p.33-45
• Main Authors: Cooper, Keith, Burdon, Daryl, Atkins, Jonathan P., Weiss, Laura, Somerfield, Paul, Elliott, Michael, Turner, Kerry, Ware, Suzanne, Vivian, Chris
• Format: Article
• Language: English
• Subjects: Aggregate dredging; Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Brackish; Brackish water ecosystems; case studies; Conservation of Natural Resources - economics; Conservation, protection and management of environment and wildlife; Cost-Benefit Analysis; dredging; Ecosystem; Ecosystem goods/benefits; Ecosystem services; Ecotoxicology, biological effects of pollution; Environmental degradation: ecosystems survey and restoration; Environmental Monitoring; Environmental Restoration and Remediation - economics; Estuaries; Fundamental and applied biological sciences. Psychology; General aspects; Geologic Sediments; Impacts; Marine; Marine and brackish environment; North Sea; physical properties; Restoration; Synecology; United Kingdom; water pollution
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2013.08.009

•The case for restoration of a former marine aggregate dredging site is examined.•We identify possible restoration techniques, costs, and the likelihood of success.•Justification is assessed in relation to ecosystem services and goods/benefits.•A cost/benefit analysis suggests restoration would not be warranted.•The need to better define ‘acceptable seabed condition’ post-dredging is stressed. Physical and biological seabed impacts can persist long after the cessation of marine aggregate dredging. Whilst small-scale experimental studies have shown that it may be possible to mitigate such impacts, it is unclear whether the costs of restoration are justified on an industrial scale. Here we explore this question using a case study off the Thames Estuary, UK. By understanding the nature and scale of persistent impacts, we identify possible techniques to restore the physical properties of the seabed, and the costs and the likelihood of success. An analysis of the ecosystem services and goods/benefits produced by the site is used to determine whether intervention is justified. Whilst a comparison of costs and benefits at this site suggests restoration would not be warranted, the analysis is site-specific. We emphasise the need to better define what is, and is not, an acceptable seabed condition post-dredging.