Tidal marsh

A tidal marsh (also known as a "tidal wetland") is a marsh found along rivers, coasts and estuaries which floods and drains by the tidal movement of the adjacent estuary, sea or ocean.[1] Tidal marshes experience many overlapping persistent cycles, including diurnal and semi-diurnal tides, day-night temperature fluctuations, spring-neap tides, seasonal vegetation growth and decay, upland runoff, decadal climate variations, and centennial to millennial trends in sea level and climate. They are also impacted by transient disturbances such as hurricanes, floods, storms, and upland fires.


Tidal marshes are differentiated into freshwater, brackish and salt according to the salinity of their water. Coastal marshes lie along coasts and estuarine marshes inland within the tidal zone. Location reveals much about the origin, controlling processes, age, disturbance regime, and future of a tidal marsh. Tidal freshwater marshes are further divided into deltaic and fringing types.[2] Extensive research has been conducted on deltaic tidal freshwater marshes in Chesapeake Bay,[3] which saw many form as a result of historic deforestation and intensive agriculture.[4]

Internally, individual marshes of each salinity level are commonly zoned into lower marshes (also called intertidal marshes) and upper or high marshes, based on their elevation above sea level.[1][5] In tidal freshwater marshes there can also be a middle marsh zone.[6]

Tidal marshes may be further classified into back-barrier marshes, estuarine brackish marshes and tidal freshwater marshes, according to the degree of the influence of the sea level.[5]


Coastal wetlands are found within coastal watersheds and encompass a variety of types including fresh and salt marshes, bottomland hardwood and mangrove swamps, and palustrine wetlands. [7] These areas provide vast benefits to the ecosystem. They serve as flood protection to upland areas by storing ground water. Additionally, shoreline erosion is impeded by the ability of wetland plants to counter wave action. Coastal wetlands act as intricate filtration systems for watersheds. [8] As water run-off travels from higher elevations to open water, the coastal wetland areas absorb and trap pollutants. These areas also provide habitat to many creatures, especially as spawning grounds and home to "feeder fish" that lie low on the food chain. They also serve as crucial rest-stops for migratory birds.

Island and barrier island

Tidal Marshes also form between a main shoreline and barrier islands. These elongate, often shifting landforms evolve parallel and close to the shoreline of a tidal marsh.[9] Many become fully submerged at high tide and exposed as directly attached to the mainland at low. Some mechanisms of barrier island formation are offshore bar theory, spit accretion theory, and climate change.[10][11] The presence of saline resistant plants does not prevent or materially impact erosion rates of tidal marsh islands, being subordinate to soil type.[12]

See also

  • Salt marsh – A coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides
  • Brackish marsh
  • Mudflat, also known as Tidal flat

External links


  1. ^ a b [1] U.S. Environmental Protection Agency: Tidal marshes
  2. ^ Pasternack, G. B. 2009. Hydrogeomorphology and sedimentation in tidal freshwater wetlands. In (A. Barendregt, A. Baldwin, P. Meire, D. Whigham, Eds) Tidal Freshwater Wetlands, Margraf Publishers GmbH, Weikersheim, Germany, p. 31-40
  3. ^ "Dr. Gregory B. Pasternack - Watershed Hydrology, Geomorphology, and Ecohydraulics :: Tidal Freshwater Deltas". pasternack.ucdavis.edu. Retrieved 2017-06-11.
  4. ^ Pasternack, Gregory B.; Brush, Grace S.; Hilgartner, William B. (2001-04-01). "Impact of historic land-use change on sediment delivery to a Chesapeake Bay subestuarine delta". Earth Surface Processes and Landforms. 26 (4): 409–427. doi:10.1002/esp.189. ISSN 1096-9837.
  5. ^ a b "Responding to Changes in Sea Level", by Marine Board, Marine Board, National Research Council (U.S.) p. 65
  6. ^ Pasternack, Gregory B.; Hilgartner, William B.; Brush, Grace S. (2000-09-01). "Biogeomorphology of an upper Chesapeake Bay river-mouth tidal freshwater marsh". Wetlands. 20 (3): 520–537. doi:10.1672/0277-5212(2000)020<0520:boaucb>2.0.co;2. ISSN 0277-5212.
  7. ^ EPA, OW, US (2015-04-06). "Coastal Wetlands - US EPA". US EPA.
  8. ^ Carter, V. 1997. Technical Aspects of Wetlands: Wetland Hydrology, Water Quality, and Associated Functions. United States Geological Survey Water Supply Paper 2425
  9. ^ Davis, Richard A. "Barrier Island System - a Geologic Overview." Geology of Holocene Barrier Island Systems. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. N. pag. Print.
  10. ^ Hoyt, John H (1967). "Barrier Island Formation". Geological Society of America Bulletin. 78 (9): 1125–1136. doi:10.1130/0016-7606(1967)78[1125:bif]2.0.co;2.
  11. ^ Kolditz, K.; Dellwig, O.; Barkowski, J.; Bahlo, R.; Leipe, T.; Freund, H.; Brumsack, H.-J. (2012). "Geochemistry of Holocene salt marsh and tidal flat sediments on a barrier island in the southern North Sea (Langeoog, North-west Germany)". Sedimentology. 59 (2): 337–355. doi:10.1111/j.1365-3091.2011.01252.x.
  12. ^ R. A. Feagin, S. M. Lozada-Bernard, T. M. Ravens, I. Möller, K. M. Yeagei, A. H. Baird
Bartletts Island

Bartlett's Island: is a residential island within the marshlands of Marshfield, Massachusetts. The island is located in the North and South River Estuary, surrounded by the salt marshes of the historic North River and is bordered by Macomber's Creek to the south and the North River to the north, just downhill from "The Hills" The rivers' watershed is a great tidal marsh with fantastic fish and wildlife habitats (on its isolated Islands - Truants and Pine Island, which are in the adjacent "English Salt Marsh" bordering the South River). The North River is a river, approximately 12 miles long formed by the confluence of the Indian Head River and Herring Brook flowing from Pembroke, MA to Scituate.

The island itself is sand based and is relatively heavily wooded. Two roads (Nathaniel Way and Bartlett Island Way) service 17 residential homes. While it is an island that is totally surrounded by water at high tide, is connected to the mainland via a causeway and is therefore always accessible (and often not perceived as an island in its truest sense). Roughly half of the homes have dock access via Macomber's Creek to the rivers and the Atlantic.

The Spit:

Bartlett's Island is located directly west of the "New Inlet" - the mouth of the North and South Rivers. At low tide, "The Spit" a vast expanse of sand is exposed, making it a favorite boating / beach spot on Boston's South Shore. The upper part of the Spit peninsula is a nesting ground for piping plovers and generally protected during the summer months. It is critical to avoid stepping on the dunes and the seagrass in order to protect the vegetation that forms and holds this beautiful resource. The New Inlet is considered one of the more treacherous inlets along the eastern seaboard, but continues to be one of the most popular boating and beach locations on the south shore.

Big Lagoon State Park

First acquired in 1977, Big Lagoon State Park is a 705-acre (2.85 km2) Florida State Park located on the northwestern Florida coast, approximately 10 miles (16 km) southwest of Pensacola on Gulf Beach Highway. It encompasses the northern boundary of Big Lagoon as it snakes toward Pensacola Bay to the east. Wild Grande Lagoon and its minor tributaries lay within the boundaries of the park, as does the alligator-inhabited Long Pond, a man-made freshwater pond.

The park is a 'gateway site' for the Great Florida Birding Trail. It features nine distinct natural communities including estuarine tidal marsh, mesic flatwoods, wet flatwoods, and is dominated by scrubby flatwoods. The park features a number of threatened and endangered species such as the large-leaved jointweed, gopher tortoise, migratory shorebirds such as snowy plover, least tern among some twenty other listed species.

From Big Lagoon, the Florida Park Service manages two neighboring state parks - Perdido Key State Park to the southwest and Tarkiln Bayou Preserve State Park to the north.

Brackish marsh

Brackish marshes develop by salt marshes where a significant freshwater influx dilutes the seawater to brackish levels of salinity. This commonly happens upstream from salt marshes by estuaries of coastal rivers or near the mouths of coastal rivers with heavy freshwater discharges in the conditions of low tidal ranges.

Chesapeake Bay National Estuarine Research Reserve (Maryland)

The Chesapeake Bay National Estuarine Research Reserve is an estuary reserve in Maryland.

The Chesapeake Bay is the largest estuary in the United States and is one of the most productive bodies of water in the world. The Chesapeake Bay National Estuarine Research Reserve reflects the diversity of estuarine habitats found within the Bay and consists of three components:

A 2,087 acres (8.45 km2) freshwater tidal marsh at Jug Bay Wetlands Sanctuary located 20 miles (32 km) from Washington, D.C.

A 726 acres (2.94 km2) freshwater tidal marsh at the Otter Point Creek component 19 miles (30 km) northeast of Baltimore

A 3,426 acres (13.86 km2) salt marsh at the Monie Bay component located 20 miles (32 km)from Salisbury, Maryland.Monie Bay was designation as a reserve in 1985. Jug Bay and Otter Point Creek were designated in 1990

The purpose of the 6,249 acres (25.29 km2) Maryland Reserve, managed by the Maryland Department of Natural Resources, is to manage protected estuarine areas as natural field laboratories and to develop and implement a coordinated program of research, monitoring, education and volunteer activities.

Corte Madera Creek (Marin County, California)

Corte Madera Creek is a short stream which flows southeast for 4.5 miles (7.2 km) in Marin County, California. Corte Madera Creek is formed by the confluence of San Anselmo Creek and Ross Creek in Ross and entering a tidal marsh at Kentfield before connecting to San Francisco Bay near Corte Madera.

Cumberland Marsh Natural Area Preserve

Cumberland Marsh Natural Area Preserve is a Natural Area Preserve located in New Kent County, Virginia near the Cumberland Hospital Children-Adolescents. Owned by the Nature Conservancy, it preserves 1,193 acres (4.83 km2) of freshwater tidal marsh along the Pamunkey River, providing habitat for bald eagles, osprey, blue herons, and egrets, as well as for the sensitive joint-vetch. It is an important habitat for wintering waterfowl as well.

Featherstone National Wildlife Refuge

The Featherstone National Wildlife Refuge is a National Wildlife Refuge located along the Potomac River in Virginia, at the point where it meets Neabsco Creek. The 325 acres (1.32 km2) of tidal marsh has been administered by the United States Fish and Wildlife Service since 1970; currently, it is part of the Potomac River National Wildlife Refuge Complex. The refuge covers wetlands and woodlands, and has a railroad right-of-way bordering its western edge. It is currently closed to the public, but has been considered as a possible portion of the route for the Potomac Heritage National Scenic Trail.

Fort Clinch State Park

The Fort Clinch State Park is a Florida State Park, located on a peninsula near the northernmost point of Amelia Island, along the Amelia River. Its 1,100 acres (4 km2) include the 19th-century Fort Clinch, sand dunes, plains, maritime hammock and estuarine tidal marsh. The park and fort lie to the northeast of Fernandina Beach at the entrance to the Cumberland Sound.

Harbor Island, South Carolina

Harbor Island is a small resort island located 14 miles (22 km) east of Beaufort, South Carolina. It is one of the Carolina Sea Islands. There is a swing drawbridge, Harbor River Bridge, that connects the island to Saint Helena Island towards the west. A small causeway crossing Johnson Creek connects Harbor Island with Hunting Island towards the south.

The majority of the island is tidal marsh, though approximately 800 acres (3.2 km2) of upland acreage exist on the northeastern portions of the island.

John Heinz National Wildlife Refuge at Tinicum

The John Heinz National Wildlife Refuge at Tinicum is a 1000-acre (4.05 km2) National Wildlife Refuge spanning Philadelphia and Delaware counties in Pennsylvania. Located in Tinicum Township, the refuge is adjacent to the Philadelphia International Airport. Established in 1972 as the Tinicum National Environmental Center, it was renamed in 1991 after the late H. John Heinz III who had helped preserve Tinicum Marsh.

The refuge serves to protect the largest remaining freshwater tidal marsh in Pennsylvania; approximately 350 acres (0.8 km2). When land acquisition is complete, the refuge will consist of 1200 acres (4.9 km2) of varied habitats.

Kenilworth Park and Aquatic Gardens

Kenilworth Park & Aquatic Gardens is a National Park Service site located in the north eastern corner of Washington, D.C., and the Maryland state border. Nestled near the banks of the Anacostia River and directly west of the Baltimore–Washington Parkway, Kenilworth Park & Aquatic Gardens preserves a plethora of rare waterlilies and lotuses in the cultivated ponds near the river. The park also contains the Kenilworth Marsh, the only remaining tidal marsh in Washington, D.C. and an adjacent recreational area.

Marina Green

The Marina Green in San Francisco, California, is a 74-acre (300,000 m2) expanse of grass between Fort Mason and the Presidio. It is adjacent to San Francisco Bay, and this location provides good views of the Golden Gate Bridge, Angel Island, Alcatraz Island, and parts of Marin County. Houses built mostly in the 1920s and 1930s line Marina Boulevard, the southern boundary of the Marina Green. Many of these houses have large bay windows, and Herb Caen, the late San Francisco newspaper columnist, often made references to the immaculate furnishings behind these windows. In the past, a railroad track along the southern edge of the Marina Green allowed the San Francisco Belt Railroad to serve the Presidio. Adjacent to the Marina Green is a marina, home to the St. Francis Yacht Club and the Golden Gate Yacht Club. The San Francisco Bay Trail runs through the green.

Prior to the 1906 earthquake, this area was a tidal marsh. After the earthquake, much of the resulting rubble was dumped here. Later, to provide land for the 1915 Panama-Pacific International Exposition, this site and the adjacent neighborhood (now the present day Marina District) was filled in. A nearby remnant of the Exposition is the restored Palace of Fine Arts.

For a short time beginning September 9, 1920 through 1944, Marina Green served as Montgomery Airfield named in honor of pioneer aviator John J. Montgomery and also as Marina Airfield and was the first terminus of the United States Post Office Department Transcontinental Air Mail Service coast to coast air mail route.

The Marina Green also served as the location for the first flights of the Hiller XH-44 helicopter, the first coaxial helicopter to fly in America, an aircraft currently in the collection of the Smithsonian Institution.The San Francisco Parks and Recreation Department currently administers the Marina Green.

Neabsco Creek

Neabsco Creek is a 13.9-mile-long (22.4 km) tributary of the lower tidal segment of the Potomac River in eastern Prince William County, Virginia. The Neabsco Creek watershed covers about 27 square miles (70 km2). The name Neabsco is derived from a Doeg village recorded as Niopsco by early English colonists. The creek has served as a vital waterway for trade and commerce in northern Virginia since the eighteenth century.

The Neabsco's watershed is highly developed because of its proximity to the I-95 corridor and the Washington, D.C. metropolitan area. The EPA Office of Water recently identified the Neabsco Creek watershed as an "area of significant habitat degradation due to a loss of natural land cover and storm water management facilities designed without consideration for environmental conditions." Most of Dale City and Woodbridge empty into Neabsco Creek.

Prince William County has made significant investments to offset stormwater impacts throughout the watershed. The U.S. Army Corps of Engineers proposal to dredge Neabsco Creek to help alleviate flooding on Route 1 was never funded, and the area continues to flood on a routine basis. Congressman Tom Davis secured more than $4 million in funds to clean up the Dale Service Corporation's sewage treatment plant on Neabsco Creek.

Local organizations often use Neabsco Creek to highlight the values of efforts to prevent damages to waterways. What has happened to the Neabsco is unfortunate, particularly because it was preventable. Now that the damage to this watershed has been done, repairs require significant investments of tax dollars and will never restore the Neabsco to its natural state.

Featherstone National Wildlife Refuge, 325 acres (1.32 km2) of tidal marsh and riparian wetlands and woodlands, is located about 22 miles (35 km) south of Washington, D.C. at the confluence of Neabsco Creek and the Potomac River and provides a habitat for neotropical migrants, waterfowl, ospreys, and historically bald eagles.

Neabsco Creek is the site of Neabsco Iron Works, one of the first iron production furnace plantations in northern Virginia. It operated on the creek from 1737 to 1820 at a site just above the present-day I-95 crossing.

Rancocas State Park

Rancocas State Park is a 1,252 acres (5.07 km2) protected area designated as a state park located in Hainesport Township and Westampton Township, Burlington County, New Jersey in the United States. Established in 1965, it is overseen and operated by the New Jersey Division of Parks and Forestry. The park is located along the North Branch of the Rancocas Creek and an extensive freshwater tidal marsh.

Seal Slough

Seal Slough is a narrow winding tidal channel through a tidal marsh in San Mateo and Foster City, California. This slough has been the object of a wetland restoration project in recent years to enhance habitat value. Dredging has been carried out in Seal Slough since at least 1954. When the original sewage treatment plant for the city of San Mateo was constructed in 1935, its discharge was directed to Seal Slough.The marshy area through which Seal Slough meanders is a productive brackish wetland whose dominant flora is cordgrass. There are a number of significant wildlife features associated with Seal Slough, including use by the endangered California clapper rail. A tide gate near the mouth of Seal Slough regulates tidal influx from San Francisco Bay to the Marina Lagoon; this flushing action is important to prevent population explosion of midges in the local area.

Seatuck National Wildlife Refuge

Seatuck National Wildlife Refuge is located in the hamlet of Islip, New York, on the south shore of Long Island. It is managed by the U.S. Fish and Wildlife Service as part of the Long Island National Wildlife Refuge Complex. The refuge consists of 196 acres (0.79 km2) bordering the Great South Bay, separated from the Atlantic Ocean only by Fire Island. Situated in a heavily developed urban area along Champlin Creek, the refuge is an oasis for many species of migratory birds and waterfowl.

Approximately one half of the refuge consists of tidal marsh, which serves a vast number of waterfowl in the winter months. The refuge attracts waterbirds, white-tailed deer, red fox, and migratory songbirds and raptors. The refuge has been classified as part of the larger Great South Bay, a significant coastal habitat. Management activities include forest and grassland protection and management, wetland restoration, wildlife nesting structure maintenance, and habitat restoration.

Sprague River (Maine)

The Sprague River is a 2.5-mile-long (4.0 km) river in the town of Phippsburg, Maine. It flows primarily through tidal marsh and empties into the Atlantic Ocean, 1.5 miles (2.4 km) west of the mouth of the Morse River and 3.5 miles (5.6 km) west of the mouth of the Kennebec River.

Suisun Bay

Suisun Bay ( sə-SOON) is a shallow tidal estuary (a northeastern extension of the San Francisco Bay) in northern California. It lies at the confluence of the Sacramento and San Joaquin Rivers, forming the entrance to the Sacramento–San Joaquin River Delta, an inverted river delta. Suisun Marsh, the tidal marsh land to the north, is the largest marsh in California. Grizzly Bay forms a northern extension of Suisun Bay. The bay is directly north of Contra Costa County.

The bay was named in 1811, after the Suisunes, a Native American tribe of the area. The word originates with the Patwin.

On the west, Suisun Bay is drained by the Carquinez Strait, which connects to San Pablo Bay, a northern extension of San Francisco Bay. In addition to the major bridges at the Carquinez Strait, it is spanned in its center by the Benicia-Martinez Bridge and at its eastern end by the State Route 160 crossing (Antioch Bridge) between Antioch and Oakley.

It is the anchorage of the Suisun Bay Reserve Fleet, a collection of U.S. Navy and merchant reserve ships, which was created in the period following World War II. The Glomar Explorer was anchored here after recovering parts of a sunken Soviet submarine in the mid-1970s (see Project Azorian). Many ships were removed and sold for scrap in the 1990s. In 2010, plans were announced to remove the mothball fleet in stages, with final removal by 2017.

The Central Pacific Railroad built a train ferry that operated between Benicia and Port Costa, California from 1879 to 1930. The ferry boats Solano and Contra Costa were removed from service when the nearby Martinez railroad bridge was completed in 1930. From 1913 until 1954 the Sacramento Northern Railway, an electrified interurban line, crossed Suisun Bay with the Ramon, a distillate-powered train ferry.

On April 28, 2004, a petroleum pipeline operated by Kinder Morgan Energy Partners ruptured, initially reported as spilling 1,500 barrels (264m³) of diesel fuel in the marshes, but, this was later updated to about 2,950 barrels. Kinder Morgan pleaded guilty to operating a corroded pipeline (and cited for failing to notify authorities quickly after the spill was discovered) and paid three million dollars in penalties and restitution.

Tidewater (region)

Tidewater is a reference to the Atlantic coastal plain region of the United States of America. It includes the low-lying plains of southeast Virginia, northeastern North Carolina, southern Maryland and the Chesapeake Bay. The area got its name from the effects of the changing tides on local rivers, sounds, and the ocean; there is also a cultural heritage that sets the Tidewater regions apart from other parts of the United States. Tidewater region was founded on principles of English gentry in a developing nation where patriotism, freedom and waterborne livelihoods existed. Dialects are distinctive and eroding along with islands and shoreline.

Tidewater region is generally flat and low flooded river plains composed of tidal marsh and large expanses of swamp. Much of the area is covered with pocosin and the higher areas are used for agricultural farmlands. Geographically, in North Carolina and Virginia the Tidewater area is the land between the Suffolk Scarp and the Atlantic Ocean. In Maryland the Tidewater area is the flooded river areas below the Fall Line. The Hampton Roads area of Virginia is considered to be a Tidewater region. Southern Maryland and the Eastern Shore, parts of Delaware round out the northern part of the region on the Chesapeake and Delaware Bays.

The term tidewater may be correctly applied to all portions of any area, including Virginia, where the water level is affected by the tides (more specifically, where the water level rises when the tide comes in). In the case of Virginia, the Tidewater region includes the land east of the Fall Line, the natural border with the Piedmont Region. It includes Hampton Roads, the rest of the Virginia Peninsula, the Middle Peninsula, the Northern Neck, and the Eastern Shore.

Planters in the early American colonies extended their tobacco productions above the Fall Line, where waterfalls or rapids mark the end of the Tidewater and the beginning of the foothill region known as the Piedmont.Tidewater is host to flora commonly associated with the South Atlantic pine forests and lower Southeast Coastal Plain maritime flora, the latter found primarily in southeastern Virginia.

Classification systems

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.