A swamp is a flat, poorly drained area with a permanent or temporary stagnant body of water covered by vegetation. The sheet of water is formed by flooding due to rains, by flooding when rivers or lakes overflow, or by the action of the tides.
Freshwater marshes are known as swamps or estuaries and swamps if they are coastal saltwater areas. These ecosystems are considered wetlands, therefore, they are within the RAMSAR agreement, due to their importance in the water cycle.
The swamp is characterized by having a periodic cycle of inundation or inundation and low content of dissolved oxygen in the water. Soils tend to be heavy, with poor drainage and a predominance of reducing processes with the presence of ferrous iron.
The vegetation is composed of rooted and floating aquatic plants, including trees tolerant to excess water. The flora that makes up this vegetation is highly variable, depending on the type of swamp and the latitude in which it develops.
The swamp fauna includes several species of amphibians (frogs, toads), reptiles, among which the species of alligators and different species of mammals stand out. In addition, the swamp, like other wetlands, has a great diversity of birds.
Across the world, there are numerous swamp areas that make up a large and varied biome. Among them is the extensive swamp area of South America between Brazil, Argentina and Paraguay, called Gran Pantanal in Brazil and estuaries in the other two countries.
In North America, the Everglades swamps in Florida (USA) are known. And in Europe there is the Sjaunja swamp in Sweden.
Relief and hydrology
Swamps occur in low, flat or concave areas, with poor drainage characterized by the presence of a shallow water table and abundant vegetation. This sheet of water can be present permanently or for long periods of time.
The water comes from the overflow of rivers or lakes (floods) or rain, combined with poorly drained soils and little infiltration (flooding).
As the water depth in the swamp is shallow and the aquatic and swamp vegetation is abundant, dissolved oxygen is scarce. In addition, the amount of suspended organic matter and dissolved organic acids in the water is high and therefore the pH is acidic.
Because they are soils subject to permanent or almost permanent flooding, they are anoxic (absence of pure oxygen), with difficulty in gas exchange. Soil structure is also affected by the breakdown of particles due to water, which makes cementing difficult.
These soils undergo reduction processes, such as denitrification (conversion of nitrates into nitrogen). They are usually heavy soils, that is, with a high content of clays in their texture.
Gray-green soil layers are produced as a result of the presence of ferrous iron by reduction processes.
Due to excess water, acidic pH and bacterial action, a partial decomposition of organic matter occurs. A hydrogen loss process is generated and under these conditions a compact carbonaceous material called peat is formed.
The combination of aerobic areas (with free oxygen) and other anaerobic areas (without oxygen) causes the development of several processes. In swamps, there is an increase in the activity of decomposing organisms.
The climate is highly variable as swamps are located in both tropical and temperate and cold zones.
Types of swamps
Swamps are classified according to different criteria, either by the salinity of the water that composes it, or by the type of vegetation that inhabits it.
salt water marsh
Corresponds to the so-called marshes which are coastal marshes usually associated with estuaries. These swamps are formed in depressions near the estuaries due to the overflow of rivers.
They occur in sandy soils, but flooded by high water table (groundwater fed by a nearby river). The type of vegetation that occurs is swamp pasture, with a predominance of rushes, rushes and grasses, in addition to algae and other aquatic plants.
fresh water swamp
This type of swamp occurs in inland depressions due to flooding by rain or overflowing bodies of water. The soil is usually clayey and the vegetation can be more complex, with trees, shrubs and herbs.
The plant species that inhabit swamps must be adapted to the permanent presence of water. In cases of salt marshes, the salinity limiting factor is added.
The swamp ecosystem is not uniform, with several areas of emerging land alternating with large areas of flooding. This determines a distribution of the species according to their ability to support the pumpkin (excess water).
In such a way that they are found from submerged, rooted and floating aquatic species, to others that do not resist long floods.
Herbs and shrubs
Among the deep-rooted grass in flooded areas are reeds (Juncaceae). While among the floats are the bora ( Eichhornia spp.) and several species of Nymphaea .
In swamp areas, halophyte species predominate, that is, resistant to saline substrates. Among them are saladillo ( Sporobolus virginicus ) and salted Swiss chard ( Limonium vulgare ).
Other halophytes are Atriplex (called salt plants) and corsets ( Spartina spp.). Also, in many marshy areas of the world, the eneas or cattails ( Typha latifolia ) and shrubs such as the marsh rose ( Rosa palustris ) occur in North America.
Other species are the labón or palo cruz tree ( Tabebuia nodosa ), the curupí ( Sapium haematospermum ) and palm trees such as the pindó ( Syagrus romanzoffiana ).
Even in temperate zones, there is a swamp conifer, the swamp cypress ( Taxodium distichum ), typical of the swamps of Louisiana (USA). Also a species of the genus Quercus , the American marsh oak or marsh oak ( Quercus palustris ).
Likewise, the aquatic tupelo ( Nyssa aquatica ) is a feature of the angiosperms of the marshy areas of the southeastern United States.
In tropical swamps inhabit the capybara ( Hydrochoerus hydrochaeris ), the marsh deer ( Hipppocamelus antisensis ) and birds such as the great white heron ( Jabiru mycteria ). There are also species of crocodiles ( Caiman crocodilus, Caiman yacare . Crocodylus moreletii ) and anaconda ( Eunectes murinus ).
In subtropical or temperate swamps, large reptiles such as Alligator mississippiensis and Crocodylus acutus are found . And mammals like the Canadian otter ( Lontra canadensis ), as well as birds like the flamingo ( Phoenicopterus ruber ).
Examples of swamps in the world
– The Great Pantanal (Brazil)
This swampy area is located in the Brazilian states of Mato Grosso and Mato Grosso do Sul. It is the largest wetland in the world, covering about 140,000 km 2 . The swamp is a flooded savannah, with submerged and floating and rooted herbaceous vegetation, and some emergent areas where arboreal vegetation grows.
The Great Pantanal is home to around 1,600 plant species. This region of South America continues with the Iberá estuaries in Argentina and the Ñeembucú estuaries in Paraguay.
From a biogeographic point of view, this area is influenced by the Amazon rainforest, the Brazilian cerrado and the Paraguay River aquatic system.
It has a seasonal tropical climate, with abundant rainfall in the rainy season and high average temperatures.
Several feline species live here, such as the jaguar ( Panthera onca ) and the jaguar ( Herpailurus yagouaroundi ). As well as a great diversity of primates, reptiles, amphibians, birds and the Caribbean manatee ( Trichechus manatus ).
This region constitutes the largest swamp of prairies flooded by rainwater in the world, with a great diversity of flora and fauna. It is located on the southern tip of the Florida Peninsula in the United States.
The meaning of its name translated into Spanish is “eternal light green”, being the name in the Spanish colony “Cañaveral de la Florida”.
The Everglades extend to Lake Okeechobee to the north, connecting with the Big Cypress Swamp (Great Cypress Swamp ). This entire group of swamps contains around 11,000 species of plants, including 25 species of orchids.
Nymph species ( Nymphaea spp.) Abound in bodies of water. While on the islands of the trees there are tropical species, such as the red bay ( Persea borbonia ) and the Cuban berry or lagoon apple ( Anona glabra ).
It has a subtropical climate with two seasons, one rainy and one dry, with high rainfall and very hot temperatures in the summer and cool in the winter.
The Everglades swamp contains a significant diversity of birds with around 300 species, as well as fish with 150 species. There are also 17 species of mammals, such as the manatee ( Trichechus manatus ), as well as 30 species of reptiles and 14 of amphibians.
Pantanos de Centla Biosphere Reserve (Mexico)
This swamp is located in the state of Tabasco (Mexico), in the south of the Gulf of Mexico. It is a biosphere reserve, which constitutes the largest wetland in North America, with more than 300,000 Ha.
It is formed by the contributions of the Grijalva and Usumacinta rivers, which are the largest in Mexico. In this wetland there is an important diversity of aquatic vascular plants, with 569 species.
The reserve includes areas of mangroves, semideciduous forests and several swamp and aquatic communities. Among the trees, cedars ( Cedrela ) , mahogany ( Swietenia ) and kapok ( Ceiba ) stand out.
Floating plants such as mouse ear ( Lemna minor ) and nymphs ( Nymphaea odorata and N. ampli ) occur in water bodies .
It is a humid and hot tropical climate, with abundant rainfall in the astronomical summer and two dry periods.
The manatee ( Trichechus manatus ) can be found, as well as a great diversity of birds with around 255 species. It also highlights the diversity of species of terrestrial and aquatic turtles, with species such as the guao ( Staurotypus triporcatus ).