In Virginia's coastal plain, the Northern Harrier nests in salt and brackish marshes. Many popular field guides provide detailed descriptions and illustrations of all these birds. In addition to providing habitat for marsh-nesting birds, marshes are great reservoirs of energy and nutrients and provide habitat for numerous plant and animal species. They are tremendous nurseries for marine life and are a source of nutrients for shellfish. Marsh vegetation controls soil and water runoff from upland areas, helping to protect rivers, bays and adjacent lands from flooding.
Marshes also help control sedimentation, eutrophication, and pollution of waterways.
Within these broad categories, more specific types can be distinguished, such as low and high marshes in the tidal salt marsh. Each marsh type is associated with characteristic plants which are adapted to prevailing conditions including frequency of flooding by tides and levels of salt in the water. Marsh Distribution Salt marshes are found along the coast behind barrier islands and beaches, and the lower portion of the Chesapeake Bay. Brackish marshes occur along the edges of estuaries and tidal rivers and streams. Freshwater marshes occur on the tidal rivers and streams above the influence of salt water, and may also be found inland around ponds, lakes, rivers, and streams.