Sediment and Erosion Control Wetlands also help maintain water quality by controlling erosion and sedimentation. Vegetative cover over the soil will absorb most of the shock from the impact of the water, so it is less likely to loosen soil. Sediment carried by runoff will tend to be trapped in wetlands and held by ground vegetation. In shallow waters, submerged aquatic vegetation acts as a filter, as sediment clings to plants instead of floating in the water. Aquatic plants also reduce water velocity, so additional sediment tends to sink to the bottom instead of floating freely.
Shoreline vegetation decreases the force of wave action and reduces erosion in tidal areas.
Nutrient Retention and Removal Wetlands also function to remove nutrients such as nitrogen and phosphorus from the environment. The nutrients are absorbed by wetland plants for their own growth so they become less available for algae. Otherwise, algae blooms in open water may dominate the system so that little oxygen is available for other aquatic life. It is important to remember that wetlands are efficient nutrient removers to a certain point. The algae blooms in the Chesapeake Bay result from nutrient overload to the system to such an extent that wetlands and aquatic plants cannot remove all of them.