2011, Marine Ecological Surveys, Marine Aggregates Levy Sustainability Fund (MALSF), Recovery of Seabed Resources Following Marine Aggregate Extraction

Dredging for marine sands and gravels makes a significant contribution to the raw materials needed for construction work and beach replenishment in the UK. Whilst the impact of dredging on physical and biological resources is well understood less is known about how these resources recover after dredging stops. In high energy, naturally disturbed environments, physical and biological recovery is rapid because dredge tracks are quickly eroded and faunal communities are made up of many small bodied, rapidly maturing opportunistic species that are already adapted to high levels of disturbance and rapidly recolonise disturbed areas. Nevertheless, in many habitats where aggregate dredging has occurred, a return to a pre-dredge physical or biological conditions often takes years or decades if it occurs at all. In many cases a return to a similar pre-dredge condition may never be possible. This may be because of the highly variable distribution and settlement of marine organisms that occurs naturally or because sediment composition has been altered and supports a different assemblage of animals. What may be more important to recovery is the ability of a different suite of species to perform a similar function within the wider marine ecosystem. Benthic communities are often important in terms of cycling of organic particulate matter and the provision of a food resource for food chains that eventually lead to fisheries production for example. Some recent research indicates that functional recovery may occur more rapidly than recovery of community composition. This work is however, at an early stage and further studies are required to improve our understanding of the impact of aggregate dredging on marine ecosystem functioning and its recovery.