For example, the sediments under marsh vegetation absorb chlorinated hydrocarbons and heavy metals such as lead, copper and iron. The wetland also retains nitrogen and phosphorus compounds which in large amounts can lead to nuisance plant growth in fresh or coastal waters. High coastal banks act as buffers for homeowners against storm damage. Vegetated banks bind the soil, preventing erosion caused by wave and surface water flow. In a severe storm, however, banks will erode, losing some sediment that is carried off to replenish the down-drift beaches.
Dunes also can naturally replenish beaches.
Both banks and dunes, left in an undisturbed state, perform the same services as do truckloads of sand, but at much less cost. Beaches, dunes and coastal banks are dynamic systems that are continuously shifting. Our construction activities must be planned carefully in these areas in order to allow this shifting to occur. Wetlands are valuable to wildlife as a food source, nesting area and protective cover. The presence of wildlife provides recreation for hunters, bird watchers, artists and photographers.