Depression wetlands are non-tidal, isolated shallow pools of water that occur in low-lying areas. They are seasonally-wet and provide critical habitat for amphibians.
The photos below show how different the same depressional wetland can look from season to season, using the McKay Tract of the Tony Florio Woodland Beach Wildlife Area as an example.
Coastal Plain Ponds
Also known as "Delmarva Bays," Coastal Plain ponds are one type of depressional wetland. They are typically isolated and small, and are often circular or elliptical in shape. They are fed by groundwater, rainfall, or snow melt in the winter and spring and usually dry up in the summer and fall. Only approximately 6,000 acres of these wetlands remain in the state, concentrated in western parts of lower New Castle County and upper-middle Kent County. Often surrounded by woodlands, the inner, wetter zones feature a variety of low shrubs, such as buttonbush and blueberry, as well as non-woody plants.
Inner-dune Depression Meadow
Inner-dune depression meadow is another type of depressional wetland. These freshwater wetlands are restricted to the back or inner dunes of saltwater ecosystems. They develop where freshwater is supplied from groundwater and precipitation. These are normally really wet in the winter and spring and dry in late summer and fall. Soils have a shallow organic layer over sand. They are typically open and sunny, and support a diverse assemblage of grass, sedges, and rushes, as well as many species of broadleaf herbs. Due to the dynamic nature of coastal environments, these wetlands are constantly expanding, contracting, and disappearing.
Why are depression wetlands important?
Despite their isolated, seasonal nature, depressions provide critical habitat to many rare and threatened plants and animals, and are especially vital to frog and salamander breeding. Because permanent water does not exist in these areas, predatory fish cannot survive here and threaten the amphibians or their eggs. Many of these habitats have been lost already, and those remaining are vulnerable to development. Preservation of surrounding forested habitats is an important component in protecting these wetlands.
Page reviewed 3/6/19