Fresh water tidal and riparian wetlands are more diverse in type than salt or brackish wetlands. Tidal fresh water wetlands serve the same shoreline protection function as salt marshes and mangrove swamps, and are equally threatened by sea level rise. Their leaves and stems absorb wave energy in storms reducing storm damage. They slow floods, reducing flood damage. Their roots prevent erosion, trap sediments and take up chemicals and nutrients that would pollute waterways.
The rich supply of plant material produced seasonally may stay in place to become the basis for the food network of the area, or be washed downstream, as some of the park nutrient load is, to the food web of a larger body of water. In our case, the Chesapeake Bay is enriched with decayed plant material from the park wetland areas. This provides food for shell fish, larger fish, and people who eat food from the Chesapeake.
In the park, the plant material forms the base of a web that feeds microbes, micro-invertebrates, fish, amphibians, reptiles, birds and mammals.
Fresh water wetlands are also habitat to food crops such as blueberries, pawpaw, and wild rice. Some riparian fresh water wetlands are habitat to valuable woods such as bald cypress, tupelo and other woods with a natural rot resistance and beauty. The green plants in these wetlands produce oxygen during photosynthesis and shade water during the hot day, releasing heat at night, regulating water temperatures, which increases the diversity of life that can live in the water. When water becomes warm it releases oxygen to the atmosphere, creating anoxic zones. By regulating water temperatures wetlands along streams and shores help hold oxygen in the water for wildlife in the water.
Some animals in these wetlands are used for their skins such as muskrat, beaver, alligators and snakes.
The flowers and grasses of wetlands are used for ornamental purposes in landscaping, in art, and textiles.
These wetlands provide habitat for a rich variety of animals that attract tourists. Their natural noise absorbing quality make them a buffer between recreation areas and other use areas as well as being a recreational destination as is for birders, canoeists and photographers, bringing in money to local economies.
Amphibians which live in such wetlands are insect controls, and being studied as first line indicators of water quality. Enzymes in the bacteria and plants of wetlands are being used for industrial processes, bioremediation, and pharmaceuticals. The diversity of these wetlands preserves a bank of DNA for future needs such as food crops to withstand climate change, biological waxes and plastics as petroleum supplies are depleted, and fighting disease. As lumber prices soar, people are turning to wetland plants, such as grasses, as sustainable raw materials for building structures.