Dredging Issues
By Amber Skye.
There is a huge demand at present for concrete. In the UK, aggregates which are used in the concrete making process last year added up to roughly four tonnes per person. The aggregates are obtained in three ways, land quarries, recycled or secondary aggregate, or more worryingly offshore gravel and sand from the seabeds around our coast. The dredging of our coastal seabeds has been increasing in recent years, last year 24.8 million tonnes of fine sand and course gravel were removed from the seas around England and Wales. With huge scale projects like the London Olympics and Thames Gateway in the pipeline, the demand for aggregates is set to increase. Environmentalists are concerned that our marine environment could be facing long-term or irreversible damage, and that understanding the full impact of extracting aggregates is vital for its future protection.
Waves start far out at sea and sand banks act as buffers, the height of the sand banks can determine the height and strength of waves. Without sand banks waves intensify and sensitive coastal habitats such as sand dunes, sand cliffs, salt marshes and some inland coastal areas are at increased risk from erosion. The sandy environments are mobile and dynamic and are able to recover within 3 to 4 years. Whilst pits and furrows left by dredgers in gravel environments can remain for 20 years, or may even be permanent.
Along the south coast there are gravel deposits that were laid down by the movement of ancient river systems dating back to the ice age. They are complex biotopes with a lot of biological diversity. The long-term impact on deposits like these is evident at Formby on Merseyside, where dredging a hundred years ago has led to the loss of 400 meters of coastline. Each year 4 meters of the coast is reclaimed by the sea, what was once a point is now a flattened headland.
Sefton coast sand dunes are the forth largest in the British Isles. They are a site of special scientific interest and home to sand lizards and natterjack toads, if the land continues to be lost here it will have a significant impact on the infrastructure and biodiversity of the site. Living in sandy habitats are worms, molluscs, crabs, rays and sand eels.
Corals, sponges, bryozoans and anemones prefer the gravel areas, these animals are what makes these habitats so attractive to fish and in turn are food for sea birds such as fulmars and Kittiwakes. The Royal Society for the Protection of Birds has expressed concerned about any potential disturbance to the feeding grounds of sea birds. As dredging companies extend their range, their impact on these delicate environments must be understood and minimized. Pressure on the Welsh Office from the Countryside Council for Wales and Natural England, has resulted in the Severn Estuary Aggregates Working Group. They are studying a proposal from Hanson Aggregates Marine and United Marine Dredging, to dredge a million tonnes a year for ten years from an area of the Bristol Channel, the results should be known shortly.
Unfortunately there are no laws in place to protect these sensitive areas and our knowledge is limited, the sea plays a fundamental role in shaping our landscape and climate. We can only hope the Government, Industry and licensing authorities realize there is a need for proper research and shows caution before destroying an environment that may never recover.
