The coastal defence of the Netherlands doesn’t stop at the water’s edge. A considerable area of the sea is also involved. In fact, almost 8,000 km² of the North Sea is of immediate importance to coastal defence efforts. To combat the ongoing erosion of the Dutch coast – to replenish what the sea removes – sand is applied to the coast where it is needed. In 2010 these sand suppletions will involve approx. 5.3 million m3 of sand on the beach and approx. 7.9 million m³ on the foreshore ( the part of the seashore between high-water and low-water marks).
Where sand is replenished, the benthos is suffocated and organisms at that site die. Temporarily, the balance of species of worms and crustaceans can be altered.
The effects of the death of the bottom fauna are felt throughout the food chain. In addition, there are indirect effects: birds, shrimps, crabs and young flatfish are left without food and have to go live elsewhere.
Priority is given to protecting the inland area. This requires sand suppletion. After an interval of time, the benthos appears to recover in the newly applied layer of sand.