A freshwater marsh is a non-tidal, non-forested

marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found ...

wetland that contains

fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...

, and is continuously or frequently flooded. Freshwater marshes primarily consist of sedges, grasses, and emergent plants. Freshwater marshes are usually found near the mouths of rivers, along lakes, and are present in areas with low drainage like abandoned oxbow lakes. It is the counterpart to the

salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is domin ...

, an upper coastal

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

of bio-habitat, which is regularly flushed with sea water.

Vegetation

Freshwater marshes are highly productive and therefore can support a large biodiversity of vegetation. Vegetation is a key component in determining the structure of a freshwater marsh. In a freshwater marsh, there are emergent plants, floating plants, floating leaved and submerged. The primary plant in freshwater marshes are emergent plants. Emergent plants are plants with soft stems and are highly adapted to live in saturated soils. Freshwater marshes have a lengthy growing season and contain high nutrient levels in the water and substrate, which contribute to an overall high net primary production. Some of the most common plants in these areas are

cattail ''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush or reedmace, in American English as reed, cattail, or punks, in ...

water lilies ''Water Lilies'' (or ''Nymphéas'', ) is a series of approximately 250 oil paintings by French Impressionist Claude Monet (1840–1926). The paintings depict his flower garden at his home in Giverny, and were the main focus of his artisti ...

arrowheads An arrowhead or point is the usually sharpened and hardened tip of an arrow, which contributes a majority of the projectile mass and is responsible for impacting and penetrating a target, as well as to fulfill some special purposes such as si ...

, and rushes.

Animals

Many types of animals use freshwater marshes for habitat at some point in their life cycles. Birds, amphibians, reptiles, fish and macro-invertebrates can be found within freshwater marshes. Birds use freshwater marshes for nesting. Common species of birds found in a freshwater marsh include

duck Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form ...

geese A goose ( : geese) is a bird of any of several waterfowl species in the family Anatidae. This group comprises the genera '' Anser'' (the grey geese and white geese) and ''Branta'' (the black geese). Some other birds, mostly related to the she ...

, swans,

songbird A songbird is a bird belonging to the suborder Passeri of the perching birds (Passeriformes). Another name that is sometimes seen as the scientific or vernacular name is Oscines, from Latin ''oscen'', "songbird". The Passeriformes contains 5000 ...

s, swallows,

coots Coots are medium-sized water birds that are members of the rail family, Rallidae. They constitute the genus ''Fulica'', the name being the Latin term for "coot". Coots have predominantly black plumage, and—unlike many rails—they are usually ...

, and black ducks. Although shallow marshes do not tend to support many fish, they are used as a nursery to raise young. The deeper ones are home to many species, including large fish such as the

northern pike The northern pike (''Esox lucius'') is a species of carnivorous fish of the genus ''Esox'' (the pikes). They are typical of brackish and fresh waters of the Northern Hemisphere (''i.e.'' holarctic in distribution). They are known simply as a p ...

and carp.

Soil

Soils contain organic matter, air, water and mineral matter. The soil has very slow decomposition rates and is often black or brown. Soils are characterized by hue, chroma and value. The soils in wetlands are often hydric in nature, which means they are completely saturated and have no oxygen.

Hydrology

Freshwater marshes are dynamic ecosystems. Aspects of the water like depth, velocity, oxygen concentration, and temperature change frequently. Marshes can be classified based on their hydrology. Marshes can be flooded permanently, intermittently, temporarily, seasonally, and semi-permanently. Groundwater reserves, water moving across the surface and precipitation are the three main sources of water in marshes.

Functions and Services

Wetlands have many services and functions that benefit the Earth. Marshes can remove carbon from the atmosphere and store it in their biomass or the ground. Many of the wide variety of species that freshwater marshes can support, provide services to humans. Many different types of food are produced within a freshwater marsh like fruits, rice, vegetables like taro, and fish. Freshwater marshes can also provide clothing in the form of pelts and materials for building such as reeds. Freshwater marshes also provide recreational services like fishing, bird-watching, water fowl hunting, and trapping. Another important function of marshes is flood mitigation. Marshes can slow down the rate at which water is travelling and create a buffer zone to stop flooding.

Restoration

There are many different techniques to restoring a wetland. One common way freshwater marshes are restored is restoration of channelized rivers. When rivers are channelized and straightened, the marshes alongside the rivers disappear. Reverting rivers back to their natural state will allow nearby marshes to form again. Another way to restore freshwater marshes is to break down levees, dikes, and berms that impede rivers from flooding. Another technique to restore freshwater marshes is to re-plan cities and infrastructure to incorporate wetlands instead of draining them to build on them.

Notable Marshes

Florida Everglades

The

Florida Everglades The Everglades is a natural region of tropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large drainage basin within the Neotropical realm. The system begins near Orlando with the Kissimm ...

represent the largest contiguous freshwater marsh in the entire world. This immense marsh covers and is located in the southern tip of Florida. The Everglades is home to animals such as the

American Alligator The American alligator (''Alligator mississippiensis''), sometimes referred to colloquially as a gator or common alligator, is a large crocodilian reptile native to the Southeastern United States. It is one of the two extant species in the gen ...

, the Apple Snail and the Everglade Snail Kite. Alligators create depressions in the mud that retain water during the dry season. These wet depressions or alligator holes are important to fish, reptiles, and amphibians during the dry season. The vegetation of the Everglades include

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...

es,

sedges The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' wit ...

, and other emergent

hydrophyte Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that g ...

s. Continued

human development Human development may refer to: * Development of the human body * Developmental psychology * Human development (economics) * Human Development Index, an index used to rank countries by level of human development * Human evolution Human evoluti ...

, including drainage for development and polluted agriculture runoff, as well as alterations in the

water cycle The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly cons ...

, threaten the existence of the Everglades.

Okavango Delta

The

Okavango Delta The Okavango Delta (or Okavango Grassland; formerly spelled "Okovango" or "Okovanggo") in Botswana is a swampy inland delta formed where the Okavango River reaches a tectonic trough at an altitude of 930–1,000 m in the central part of the en ...

Botswana Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label= Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalaha ...

is one of Africa's largest freshwater marshes. Before the flowing water reaches the Okavango Delta, it comes from Angola and passes through Namibia. This marsh is so large that it can support commercial and recreational fishing. There are many tree islands within the Okavango marsh due to termites. Termites colonies build mounds in the dry season that later become flooded. The crowns of the mounds stay above water level and can support trees and other vegetation. The tree islands become a hot spot for biodiversity within the marsh. Continuous proposals for rerouting the river that fills the marsh is the main cause of concern for the future of this wetland.

Rift Valley

Rift Valley is located in Eastern Africa.

Lake Naivasha Lake Naivasha is a freshwater lake in Kenya, outside the town of Naivasha in Nakuru County, which lies north west of Nairobi. It is part of the Great Rift Valley. The name derives from the local Maasai name ''Nai'posha'', meaning "rough wate ...

is surrounded by tropical, freshwater marshes in the extensive 6,500 kilometer rift valley. These marshes are home to cattail, papyrus, and floating mats of other plants. This marsh is also home to ducks, herons, and crayfish. The rifting in the valley is enlarging the lake, creating more wetlands in the surrounding area.

Mesopotamian Marshlands

The Mesopotamian Marshlands are located in southern Iraq and Iran. The confluence of the Tigris and Euphrates Rivers create the Mesopotamian Marshlands. The Mesopotamian Marshlands were once the largest wetland ecosystem in the Middle East, covering an area of 15,000 to 20,000 square kilometers. In the 1980s and 1990s, this marshland was drained by upstream dams and water control structures, down to 10% of the original area. The marshland is located on the intercontinental flyway of migratory birds and is used by two-thirds of West Asia's water fowl. The marsh is currently dominated by an invasive grass, ''Phragmites australis''.

References

{{Wetlands Coastal geography Marshes