A wetland is a land area that is saturated with water, either permanently or seasonally, such that it takes on the characteristics of a distinct ecosystem. The primary factor that distinguishes wetlands from other land forms or water bodies is the characteristic vegetation of aquatic plants, adapted to the unique hydric soil. Wetlands play a number of roles in the environment, principally water purification, flood control, carbon sink and shoreline stability. Wetlands are also considered the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal life.[5
Types of Wetlands in and around the estuary
Wetland Habitats in and around the estuary include:
Salt marshes are coastal wetlands that are flooded and drained by salt water brought in by the tides. They are marshy because the soil may be composed of deep mud and peat. Peat is made of decomposing plant matter that is often several feet thick. Peat is waterlogged, root-filled, and very spongy. Because salt marshes are frequently submerged by the tides and contain a lot of decomposing plant material, oxygen levels in the peat can be extremely low—a condition called hypoxia. Hypoxia is caused by the growth of bacteria which produce the sulfurous rotten-egg smell that is often associated with marshes and mud flats.
Aquatic beds include subtidal kelp forests, intertidal eelgrass beds, and often dense stands of native or exotic species that clog waterways and annoy swimmers and boaters. They provide critical food and cover for fish, amphibians, and invertebrates, and are usually directly linked to riverine and emergent wetlands by hydrology, chemistry, and food webs. A large variety of invertebrates and vertebrates use both aquatic beds and emergent wetlands during part of their life cycles. Since 1850, much aquatic bed habitat has been lost to river channelization, siltation, and filling for agriculture or urban development.
Freshwater Emergent Wetlands
Freshwater Emergent wetlands include wet meadows, marshes, swamps, bogs, and areas where groundwater, flowing or standing surface water or ice provides a significant part of the supporting substrate for a plant community for at least five months of the year.
Forested wetlands are dominated by trees. Coniferous swamps, lowland hardwood swamps, and foodplain forests are all common types of forested wetlands. Ephemeral ponds occur in depressions in forested areas. Periodic fooding, especially following snowmelt and heavy spring rains, alternating with dry periods with lower water levels, sustains foodplain forests and hardwood swamps. Coniferous swamps occur in areas with saturated soils and high water tables.
Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of estuarinesilts, clays and marine animal detritus. Most of the sediment within a mudflat is within the intertidal zone, and thus the flat is submerged and exposed approximately twice daily.
In the past tidal flats were considered unhealthy, economically unimportant areas and were often dredged and developed into agricultural land. Several especially shallow mudflat areas, such as the Wadden Sea, are now popular among those practising the sport of mudflat hiking.
They usually support a large population of wildlife, and are a key habitat that allows tens of millions of migratory shorebirds to migrate from breeding sites in the northern hemisphere to non-breeding areas in the southern hemisphere. They are often of vital importance to migratory birds, as well as certain species of crabs,mollusks and fish.
Primary Food Production
Primary food production for the estuary comes from: 1) Estuary Salt Marshes, 2) Aquatic Beds, 3) Freshwater Emergent Wetlands and 4) Forested Wetlands. Freshwater and Forested wetlands are outside of the estuary proper but flooding carries considerable vegetative matter into the estuary.
The Freshwater Emergent Wetlands and Forested Wetlands provide areas a buffer between the estuary and developed land and protect the cities from the distractive effects of flooding.
Freshwater Emergent Wetlands and Forested Wetlands also provide a buffer between urbanized areas and the estuary. Oil and other pollutants from the developed area are filtered by these wetlands resulting in less pollution entering the estuary.