Delaware’s landscape is rich in variety of wetland habitats with each type supporting 
unique communities of plants and animals. What follows is a list of the most prominent kinds divided between salt to brackish marshes and seasonal freshwater wetlands.
Seasonal freshwater wetlands: The wetlands on this page share several features. They are largely freshwater (lack tidal inputs), usually fed by seasonal rains or high groundwater levels, and appear wet at the surface for only part of the year (typically winter through early spring). They also feature some of our most vital habitats for biodiversity in the state (including many species found nowhere else), and are also the ones most vulnerable to loss through human impacts.
Wet flatwood swamp forests are one of the most important, but least well-recognized wetland types in Delaware. Also called "winter wet woods," they occur as mixed hardwood forests in the headwaters of many coastal plain streams, and as loblolly pine/maple-gum swamps in areas fringing the Inland Bays. Due to their seasonally-wet nature, a variety of other wetland and upland plants also share the habitat.
Flatwoods provide large areas that can filter pollutants coming off the surrounding lands before they reach the stream, and are thus critical to maintaining water quality downstream. As with the other freshwater wetlands featured here, their seasonality makes wet flatwoods especially vulnerable to human impacts, and thus a critical focus for preservation efforts.
Floodplain hardwood swamps, also called ‘riparian’ or ‘riverine’ swamps, occur along the more downstream portions of some of the major rivers and their tributaries in Delaware. Historically, many were dammed to form impoundments (e.g. Killens Pond on the Murderkill, Haven Lake on the Mispillion, and Collins Pond on the Nanticoke). Those remaining feature a mix of deciduous trees, including: red maple, sweet gum, black gum, willow oak, pin oak and others.
As their name implies, floodplain swamps play a critical role in absorbing runoff reaching rivers and streams, thus reducing the impacts of floods and storms. Like the other wetland types on this page, floodplain swamps also provide vital wildlife habitat, adding to their conservation value.
Wet meadows are another freshwater wetland type that may escape notice for not appearing wet over much of the year. But they do receive sufficient groundwater; rainwater and/or snow melt to show standing water at the surface on a seasonal basis. Just below the surface, soils remain waterlogged for longer periods, supporting development of a plant community that includes a variety of reeds, sedges, rushes, asters, goldenrods and other soggy-soil adapted plants.
Wet meadows also support unique wildlife species, most notably, the endangered bog turtle. Because they appear dry at the surface for the better part of the year, wet meadows have often been viewed as non-wetland in nature and thus vulnerable to filling and draining for other uses. Where water source and soil conditions allow, wet meadows restoration projects are easily done.
Coastal plain ponds, also called Delmarva Bays, are isolated, small, shallow, seasonally-wet areas, often circular/elliptical in shape, fed by groundwater/rainfall/snow melt in winter/spring and drying up in summer/fall. Over a thousand of these exist in the state, concentrated in inland parts of lower New Castle and upper/middle Kent counties. Often surrounded by woodlands, the inner (wetter) zones feature a variety of low shrubs (e.g. buttonbush) and non-woody plants.
Despite their isolated, seasonal nature, coastal plain ponds provide critical habitat to many rare and threatened plants and animals, and are especially vital to frog and salamander breeding. Many of these habitats have been lost already, and those remaining are vulnerable to development. Preservation of adjacent contiguous forested habitats is a high conservation priority.
Other unique wetland types: The recent Delaware Comprehensive Wildlife Conservation Strategy recognizes at least 119 habitat types in the state, of which 79 are of the wetland variety. This includes several subtypes of the above-described categories, as well as various other small, but specialized, wetland types far too numerous to distinguish here.
Although the latter – featuring such catchy names as interdunal swales, sea level fens (pictured at left), and Piedmont streamside seeps – typically comprise small, off-the-beaten path kind of places – they also offer habitats unique and essential to some of our most rare and threatened species, and are thus of critical conservation concern to Delaware’s natural heritage.
Photographs courtesy of the DE Natural Heritage Program and DE Watershed Assessment Section
