The Marajó várzea (NT0138) is an
ecoregion
An ecoregion (ecological region) is an ecological and geographic area that exists on multiple different levels, defined by type, quality, and quantity of environmental resources. Ecoregions cover relatively large areas of land or water, and c ...
of seasonally and tidally flooded
várzea forest in the
Amazon biome
The Amazon biome () contains the Amazon rainforest, an area of tropical rainforest, and other ecoregions that cover most of the Amazon basin and some adjacent areas to the north and east. The biome contains blackwater river, blackwater and whitewa ...
.
It covers a region of sedimentary islands and floodplains at the mouth of the Amazon that is flooded twice daily as the ocean tides push the river waters onto the land.
The flooded forests provide food for a wide variety of fruit-eating fish, aquatic mammals, birds and other fauna.
It has no protected areas and is threatened by cattle and water-buffalo ranching, logging and fruit plantations.
Location
The Marajó várzea is at the mouth of the
Amazon River.
It covers coastal areas of the states of
Pará
Pará () is a Federative units of Brazil, state of Brazil, located in northern Brazil and traversed by the lower Amazon River. It borders the Brazilian states of Amapá, Maranhão, Tocantins (state), Tocantins, Mato Grosso, Amazonas (Brazilian st ...
and
Amapá
Amapá (; ) is one of the 26 federative units of Brazil, states of Brazil. It is in the North Region, Brazil, North Region of Brazil. It is Federative units of Brazil#List, the second-least populous state and the eighteenth-largest state by area ...
, with an area of .
Water levels are affected by freshwater flowing down the river and by tidal flows from the
Atlantic Ocean
The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...
.
The
várzea forest in the ecoregion starts where the
Xingu River
The Xingu River ( ; ; ) is a river in north Brazil. It is a southeast tributary of the Amazon River and one of the largest clearwater rivers in the Amazon basin, accounting for about 5% of its water.
__TOC__
Description and history
The fir ...
joins the Amazon, which begins to broaden out.
It covers the west of Marajó Island and many smaller islands in the Amazon channel, as well as parts of the mainland to the north and south of the river mouth including a small area of
French Guiana
French Guiana, or Guyane in French, is an Overseas departments and regions of France, overseas department and region of France located on the northern coast of South America in the Guianas and the West Indies. Bordered by Suriname to the west ...
.
The nutrient-rich sediments from the river are deposited on the islands.
The Marajó várzea ecoregion adjoins the
Xingu–Tocantins–Araguaia moist forests and the
Tocantins–Araguaia–Maranhão moist forests to the south, and the
Uatuma–Trombetas moist forests and an area of
Guianan savanna
The Guianan savanna (NT0707) is an ecoregion in the south of Venezuela, Guyana and Suriname and the north of Brazil. It is in the Amazon biome.
The savanna covers an area of rolling upland plains on the Guiana Shield between the Amazon and Orino ...
to the north. The
Gurupa várzea is upstream along the Amazon.
There are strips of
Amazon–Orinoco–Southern Caribbean mangroves along the coast.
The
Amapá mangroves are found to the north of the Amazon's mouth and the
Pará mangroves to the south.
Physical
The Marajó várzea covers flooded land at the mouth of the Amazon River.
There are many islands including the
Marajó
Marajó () is a large coastal island in the state of Pará, Brazil. It is the main and largest of the islands in the Marajó Archipelago. Marajó Island is separated from the mainland by Marajó Bay, Pará River, smaller rivers (especially M ...
island and the smaller Porcos, Pará, Mututí and Uituquara islands.
The estuary is a recent lowland that has been forming during the present
Holocene
The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
epoch, and is surrounded by
Tertiary
Tertiary (from Latin, meaning 'third' or 'of the third degree/order..') may refer to:
* Tertiary period, an obsolete geologic period spanning from 66 to 2.6 million years ago
* Tertiary (chemistry), a term describing bonding patterns in organic ch ...
deposits.
The constant action of tides and river flow form a maze of channels.
Twice daily the tides push river discharge onto the low-lying land to a depth of .
Soils in the many islands formed from the Amazon sediments are typically mottled clay with poor drainage.
The ecoregion also includes slightly higher ground that is usually not flooded.
The east of Marajó island is made of older Tertiary sediments.
It is covered by flooded savanna and humid terra firme forest.
Climate
The
Köppen climate classification
The Köppen climate classification divides Earth climates into five main climate groups, with each group being divided based on patterns of seasonal precipitation and temperature. The five main groups are ''A'' (tropical), ''B'' (arid), ''C'' (te ...
is "Am": equatorial with monsoon rainfall.
Average annual temperatures are about , ranging from about
Average annual precipitation is about .
Monthly rainfall varies from in October to over in March.
Ecology
The ecoregion is in the
Neotropical realm
The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropics, tropical Ecoregion#Terrestrial, terrestrial ecoregions of the Americas and the entire South American temperat ...
and the
tropical and subtropical moist broadleaf forests
Tropical and subtropical moist broadleaf forests (TSMF), also known as tropical moist forest, is a subtropical and tropical forest habitat type defined by the World Wide Fund for Nature (WWF).
Description
TSMF is generally found in la ...
biome.
Flora
Vegetation is dominated by palms, and is shorter and less diverse than in surrounding areas.
The most common palm species are murumuru (''
Astrocaryum murumuru''), raffia (''
Raphia taedigera''),
açaí (''Euterpe oleracea''), maripa (''
Attalea maripa''), bacaba (''
Oenocarpus bacaba''), patauá (''
Oenocarpus bataua''), buriti (''
Mauritia flexuosa
''Mauritia flexuosa'', known as the moriche palm, ''ité'' palm, ''ita'', ''buriti'', ''muriti'', ''miriti'' (Brazil), ''canangucho'' (Colombia), ''morete or acho'' (Ecuador), ''palma real'' (Bolivia), or ''aguaje'' (Peru), is a Arecaceae, palm t ...
''), ubuçu (''
Manicaria saccifera''), cashapona (''
Socratea exorrhiza'') and several species of
Geonoma palms.
There are large stands of the commercially valuable buriti and acai palms.
Among other common trees in the tidal várzea are the timber species ''
Virola surinamensis'', ''
Cedrelinga castanaeformis'', ''
Ceiba pentandra
''Ceiba pentandra'' is a tropical tree of the order (biology), order Malvales and the family (biology), family Malvaceae (previously emplaced in the family Bombacaceae), native to Mexico, Central America and the Caribbean, northern South America, ...
'', ''
Calycophyllum brasiliensis'' and other large trees such as
Ficus
''Ficus'' ( or ) is a genus of about 850 species of woody trees, shrubs, vines, epiphytes and hemiepiphytes in the family (biology), family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few spe ...
species, ''
Macrolobium acaciifolium'', ''
Pachira aquatica
''Pachira aquatica'' is a species of tropical wetland tree in the mallow family Malvaceae, native to Central and South America where it grows in swamps. It is known by its common names Malabar chestnut, French peanut, Guiana chestnut, provisio ...
'', ''
Symphonia globulifera'', ''
Triplaris surinamensis'' and ''
Mora paraensis''.
The shrub ''
Machaerium lanatum'' forms dense thickets along the banks of the rivers.
There are large lianas in the flooded areas such as ''
Strychnos blackii'', ''
Landolphia paraensis'' and ''
Guatteria scandens''.
The ecoregion also includes seasonally flooded forest and permanently flooded
igapó swamp forest.
Fauna
The várzea forest provides a mechanism for rapid capture and release of nutrients, and hosts many species of freshwater fish and aquatic mammals.
There is greater diversity of fauna than in surrounding areas.
99 species of mammals have been reported.
Big cats include
jaguar
The jaguar (''Panthera onca'') is a large felidae, cat species and the only extant taxon, living member of the genus ''Panthera'' that is native to the Americas. With a body length of up to and a weight of up to , it is the biggest cat spe ...
(''Panthera onca'') and
cougar
The cougar (''Puma concolor'') (, ''Help:Pronunciation respelling key, KOO-gər''), also called puma, mountain lion, catamount and panther is a large small cat native to the Americas. It inhabits North America, North, Central America, Cent ...
(''Puma concolor'').
Fruiting trees such as the buriti palm are sources of food for grazing animals such as
gray brocket (''Mazama gouazoubira''),
red brocket (''Mazama americana''), and
capybara
The capybara or greater capybara (''Hydrochoerus hydrochaeris'') is the largest living rodent, native to South America. It is a member of the genus '' Hydrochoerus''. The only other extant member is the lesser capybara (''Hydrochoerus isthmi ...
(''Hydrochoerus hydrochaeris'').
The estuary is home to large fish that swim through the flooded forest where they eat and spread fruit from the trees.
Fish include pacus (
Metynnis and
Mylossoma genera),
tambaqui
The tambaqui (''Colossoma macropomum'') is a large species of freshwater fish in the family Serrasalmidae. It is native to tropical South America, but kept in aquaculture and Introduced species, introduced elsewhere. It is also known by the names ...
(''Colossoma macropomum''), pirarucus (''
Arapaima gigas
''Arapaima gigas'', also known simply as Arapaima, pirarucu, or paiche,Miranda-Chumacero, G., Wallace, R., Calderón, H., Calderón, G., Willink, P., Guerrero, M., ... & Chuqui, D. (2012). Distribution of arapaima (Arapaima gigas)(Pisces: Arapaim ...
''), and sardinhas (''
Triportheus angulatus'').
Endangered species include the
white-cheeked spider monkey (''Ateles marginatus''),
black bearded saki (''Chiropotes satanas''),
giant otter
The giant otter or giant river otter (''Pteronura brasiliensis'') is a South American carnivorous mammal. It is the longest member of the weasel family, Mustelidae, a globally successful group of predators, reaching up to . Atypical of mustel ...
(Pteronura brasiliensis),
green sea turtle
The green sea turtle (''Chelonia mydas''), also known as the green turtle, black (sea) turtle or Pacific green turtle, is a species of large sea turtle of the family Cheloniidae. It is the only species in the genus ''Chelonia''. Its range exte ...
(''Chelonia mydas'') and
hawksbill sea turtle
The hawksbill sea turtle (''Eretmochelys imbricata'') is a critically endangered sea turtle belonging to the family Cheloniidae. It is the only extant species in the genus ''Eretmochelys''. The species has a global distribution that is largel ...
(''Eretmochelys imbricata'').
The endemic
short-tailed opossum (''Monodelphis maraxina'') is endangered.
Other endemic mammals are the
seven-banded armadillo (''Dasypus septemcinctus''),
Recife broad-nosed bat (Platyrrhinus recifinus),
Brazilian funnel-eared bat (''Natalus espiritosantensis''),
Greenhall's dog-faced bat (Cynomops greenhalli),
silvery marmoset (''Mico argentatus''),
red-handed tamarin (''Saguinus midas''),
Azara's night monkey (''Aotus azarae'') and
crab-eating fox (''Cerdocyon thous'').
The ecoregion is home to the endangered
West Indian manatee
The West Indian manatee (''Trichechus manatus''), also known as the North American manatee, is a large, aquatic mammal native to warm coastal areas of the Caribbean, from the Eastern United States to northern Brazil. Living alone or in herds, it ...
(''Trichechus manatus'').

There are at least 540 species of birds.
Aquatic bird species include heron and egret of the
Egretta
''Egretta'' is a genus of medium-sized herons, mostly breeding in warmer climates.
Representatives of this genus are found in most of the world, and the little egret, as well as being widespread throughout much of the Old World, has now starte ...
and
Ardea genera,
whistling duck
The whistling ducks or tree ducks are a subfamily, Dendrocygninae, of the duck, goose and swan family of birds, Anatidae. In other taxonomic schemes, they are considered a separate family, Dendrocygnidae. Some taxonomists list only one genus, ...
(Dendrocygna species),
sharp-tailed ibis (''Cercibis oxycerca''),
Theristicus species and
roseate spoonbill (''Platalea ajaja'').
Endemic birds include
white-bellied seedeater (''Sporophila leucoptera''),
grassland yellow finch (''Sicalis luteola''),
chalk-browed mockingbird (''Mimus saturninus''),
tropical pewee (''Contopus cinereus''),
rufous-throated antbird (''Gymnopithys rufigula''),
black-breasted puffbird (''Notharchus pectoralis'') and
plain-bellied emerald (''Amazilia leucogaster'').
Endangered birds include the
scaled spinetail (''Cranioleuca muelleri'') and
yellow-bellied seedeater (''Sporophila nigricollis'').
Conservation status
The ecoregion is in a region of the Amazon at the mouth of the great waterway that has long been heavily used by humans.
It is vulnerable, and has no protected areas.
Cattle and water buffalo ranches have degraded natural grasslands and forests and caused loss of food sources for capybaras, manatees and fruteating fish.
Commercial logging on Marajó island has almost eliminated some valuable native tree species.
Stands of Açaí palm planted for their commercially valuable fruit have replaced stands of native buriti palm.
Global warming will force tropical species to migrate uphill to find areas with suitable temperature and rainfall.
Low, flat ecoregions such as the Marajó várzea are extremely vulnerable.
Notes
Sources
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{{DEFAULTSORT:Marajó várzea
Ecoregions of Brazil
Amazon biome
Neotropical tropical and subtropical moist broadleaf forests