Marine aggregates (sand and gravel) have emerged as a strategic mineral resource.
Sand: naturally occurring unconsolidated rock particles between 63 and 2000 µm
Gravel: particles between 2 mm and 63 mm
They are formed by fluvial (river), lacustrine (lake), glacial, marine or residual (weathering) processes
Sand and gravel are mostly used for construction either as aggregate in concrete, as road base or as fill. It is also used for beach nourishment and shore protection and for land reclamation. Sand in industrial use represents a lower volume but a higher market value (glass making, abrasives and moulding in foundries).
Annually, approx. 40 million m3 of marine sand and gravel extracted from North European inner Continental Shelf.
15% of the extracted materials are used outside the country of production.
Need for realisation of large-scale infrastructure projects for coastal areas of Europe.
New resources must be found.
Environmental concerns must be addressed.

2. Impacts of marine sand extraction

Effects of marine aggregate extraction which have been considered include:
a) Significant alteration of regional sediment transport patterns and coastal morphodynamics:
Changes in seabed elevation may:
- alter inner shelf flows.
- enhance the wave energy towards the coast.
- change the active beach-nearshore sediment systems and budgets.
- enhance coastal erosion and retreat.
b) Harmful effects on fauna, flora and water quality in the area of mining:
- Destruction of benthic habitats and species, such as fish and shelfish populations
- The formation of turbid plumes, of fine-grained sediments, during extraction may affect the benthic ecology, far from the extraction site.
- Creation of large depressions on the seabed (depending upon extraction method) where anoxic conditions may develop.
c) Disturbance of cultural heritage sites e.g. shipwrecks of archaeological interest.
Potential conflicts of interests exist between marine aggregate industry and other sea-bed users: Fisheries, Shipping, Oil Industries, and, more recently: Offshore Windmill Farms (for power generation).