Marine aggregate dredging is a major industry which supplies raw materials to the UK construction industry, because of this it is of great importance to the countries economy, however the effects of obtaining this valuable resource from the seabed is damaging marine ecosystems, commercial fishing industries and beaches along our coastline.
Marine aggregate dredging is a form of strip mining, sand and gravel is removed from the seabed, the extraction is carried out by large vessels with a capacity of 5000 tonnes or greater by means of suction All offshore marine aggregate dredging in the UK takes place within the 12 nautical mile limit. The material obtained from the seabed is screened for suitability with over half of the material returned to the sea as unsuitable (mud, silt, shells and other unwanted constituents of the seabed)
.Licences to dredge are issued by the UK central government, which administers a licensing system set out in the marine mineral guidance note 1 (MMG1), this licensing procedure requires the applicant to undertake an environmental impact assessment based on the terms within the MMG1. When the appropriate parties have studied this the applicant can then apply to obtain a license from the crown estate (dredging takes place within the 12 mile limit and this comes under the crown estates jurisdiction) who will specify the period of license, volume of extraction and other various requirements.
Both sand and gravel beds support rich and varied biological communities, the nature of these habitats can change depending on location but both sand and gravel areas are important to both fish and other seafloor species. Marine life at the site of extraction experiences a severe rate of mortality, and the rejected constituents of the dredge smother the seabed for great areas around the extraction site. As well as the destruction of marine life, aggregate dredging also changes the morphology of the coastline, during the stormy winter months, sand and shingle are drawn from beaches and into the ocean, in comparison, in calmer weather these materials accumilate and beaches regenerate. Dredging of offshore aggregates can disturb this relationship and this can leave beaches prone to erosion, this process can be seen in Norfolk and on the Gower peninsular
The Aggregate dredging industry is rapidly emerging as an industry of great importance for the UK’s economy, however, we are not evaluating the consequences of this development. There are many things that can be done in the near future to conserve this limited resource and protect marine biodiversity:
· Better Environmental impact assessments and monitoring will enable a more sustainable and environmentally friendly practice to take place
· Less demand for marine based aggregates as a result of the development of the recycled aggregate industry
This will lead to a greater protection of current sea defences, marine communities and marine diversity.
For more information about the methods, legislation and effects of marine aggregate dredging click here