Globally, six per cent of present land surface is wetland, but the historical extent of wetlands was considerably greater worldwide and in the United States. America has a 400 year history of routinely filling in, dredging, draining, and converting wetlands to other uses—particularly agriculture. By the 1970s greater than fifty per cent of pre colonial wetlands had been destroyed, with the most pervasive damage being done between 1850 and 1950. Our growing awareness of environmental interests, scientific knowledge and legislative responsibilities over the past 25 years has led to the recognition of numerous wetland values. Federal, state and local regulatory protection has resulted.
Connecticut has an estimated 173,000 acres (70,000 hectares) of saltwater and freshwater wetlands. The state has an additional 86,500 acres (35,000 hectares) of deep water habitats (freshwater lakes and ponds). These are not trivial numbers for a small state such as ours. Anyone who has taken a flight in a small plane over Connecticut can attest to the widespread distribution of wetlands in our coastal and inland regions. (One acre, from the Imperial System of measurement, equals 43,560 sq. ft. One hectare, standard unit of land measurement in the metric system, is equal to an area 100 m by 100 m, or 10,000 sq.m.)
Wetlands are ecotones or transitional zones between uplands and deep water habitats. They are thus difficult to define by precise boundaries. The three mechanisms by which wetlands are delineated are by their hydrology (frequency of flooding), by the presence of obligate (requiring flooded conditions) and facultative (tolerating flooded conditions) wetland vegetation, and by the presence of hydric soils. Some wetlands remain flooded throughout the year, while others contain standing water for brief periods of time during the growing season. Seasonally flooded wetlands have a frequency and duration of flooding which lead to the development of hydrophilic vegetation. Wetlands have among the highest of net primary productivities of all ecosystems on earth. As suggested above, wetland ecology involves multidisciplinary study and consideration of a range of management issues.
The U.S. Fish and Wildlife Service defines wetlands as “lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water. Wetlands must have one or more of the following attributes: (1) at least periodically, the land supports predominantly hydrophytes; (2) the substrate is predominantly undrained hydric soil; (3) the substrate is non-soil and is saturated with water or covered by shallow water at some time during the growing season of each year” (Cowardin 1979). Wetlands can be large or small, ranging in size from a vernal pool a few yards across to an ecosystem the size of the Florida Everglades or Georgia’s Okefenokee Swamp.