mangrove
A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in severa ...
ecoregion
An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of ...
that covers extensive areas of the coastline
New Guinea
New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torres ...
, the large island in the western
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...
north of
Australia
Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
.
Location and description
The New Guinea mangroves cover an area of , particularly among the river mouths of the island's south coast. This ecoregion contains the greatest diversity of mangrove species in the world and they are an important habitat for wildlife. Areas of mangroves on the northern coast of New Guinea can be found at the mouths of the
Sepik
The Sepik () is the longest river on the island of New Guinea, and the second largest in Oceania by discharge volume after the Fly River. The majority of the river flows through the Papua New Guinea (PNG) provinces of Sandaun (formerly West Se ...
Cenderawasih Bay
Cenderawasih Bay ( id, Teluk Cenderawasih, "Bird of Paradise Bay"), also known as Sarera Bay ( id, Teluk Sarera) and formerly Geelvink Bay ( nl, Geelvinkbaai), is a large bay in northern Province of Papua, Central Papua and West Papua, New Guin ...
, and
Dyke Ackland Bay Dyke Ackland Bay is a large bay in the Oro Province of Papua New Guinea. The bay extends from Cape Nelson to Cape Ward Hunt. Porlock Bay and Oro Bay are some of the smaller bays located within the larger bay. The bay was named by Captain John Mores ...
and
Ward Hunt Strait
The Ward Hunt Strait is a 30 km wide stretch of water in Milne Bay, separating Papua New Guinea from Goodenough Island in the D'Entrecasteaux Islands. The Dart Reefs and Keast Reef are located in the centre of the channel.Purari,
Kikori
Kikori is a small town in the Gulf Province of Papua New Guinea.
Kikori lies in the delta of the Kikori River at the head of the Gulf of Papua. This area is particularly biologically rich with a diversity of ecosystems and densely forested, wit ...
,
Fly
Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
s as well as Bintuni Bay and other areas of the southern Bird's Head Peninsula. Some areas such as the Kikori delta have larger and thicker mangroves than others.
Climate
The coast of New Guinea has a
Tropical monsoon climate
An area of tropical monsoon climate (occasionally known as a sub-equatorial, tropical wet climate or a tropical monsoon and trade-wind littoral climate) is a tropical climate sub-type that corresponds to the Köppen climate classification category ...
Mangroves depend on a complex series of dynamic natural tidal processes that create the conditions for their survival. Rivers depositing sediment, together with waves and coastal currents, reshape the tidal zone where mangroves thrive. There are several features that all species of mangroves have in common. These include tolerance to conditions of high
soil salinity
Soil salinity is the salt (chemistry), salt content in the soil; the process of increasing the salt content is known as salinization. Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral wea ...
, tolerance to submergence in water, or waterlogged soil, and to low
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
conditions. The use of water to disperse young plants is also very characteristic of mangroves. As a result of the water-logged soil that mangrove trees reside in, they have formed adaptations to help them survive. For example, black mangroves survive in water-logged soil by using special "root snorkels" called pneumatophores. These structures are covered with small holes call
lenticel
A lenticel is a porous tissue consisting of cells with large intercellular spaces in the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants. It functions as a pore, providing a ...
s that allow the roots to breathe the same way a snorkel lets you breathe while underwater. When trying to overcome the obstacle of the salinity that these trees live in, they have a few adaptations. They can actually concentrate much of the salt concentration in older leaves, which are soon to fall off, taking the excess salt with them. Some species even have salt glands which excrete salt to the surface of the leaves allowing it to be washed away by rain.
Mangroves begin as a seed called a propagule, which germinates while still attached to the tree. The seed has a long cylindrical shape that falls off the parent tree and either sticks in the mud growing next to the parent tree, or floats off to sea. These seeds have a very strong, protective covering that allows them to float and survive for long distances and periods of time. The seedling may finally reach a point of its destination where conditions are favorable, and the roots will begin to bury into the ground, forming a new mangrove tree. The dispersal of these "live" young trees is called vivipary, or birth of live young, very similar to mammals.
Flora
The range of newly deposited and well-established areas, varying water depth, and variations in salinity from the mixing of salt and fresh water create a diversity of habitats that are home to different mixes of species. On the shoreline pioneering species like the Avicennia species '' Avicennia alba'' and ''
Avicennia marina
''Avicennia marina'', commonly known as grey mangrove or white mangrove, is a species of mangrove tree classified in the plant family Acanthaceae (formerly in the Verbenaceae or Avicenniaceae). As with other mangroves, it occurs in the inte ...
'' are usually the first to establish on coastal shores, with '' Sonneratia'' growing in the coastal tidal creeks. Their complex root networks encourage further sedimentation and growth which then creates shade that allows ''Rhizophora mucronata '' to establish itself, ultimately supplanting the shade-intolerant ''Avicennia'' and ''Sonneratia''. Then '' Rhizophora apiculata '' and ''
Bruguiera parviflora
''Bruguiera parviflora'' is a tree in the family Rhizophoraceae. The specific epithet ' is from the Latin meaning "small flowers".
Description
''Bruguiera parviflora'' grows up to tall with a trunk diameter of up to . The bark is pale grey to p ...
'', (and occasionally '' Bruguiera gymnorhiza'') are the next in succession but still in waters that are more than 10% saline. Mature mangrove forests include '' Xylocarpus'', Lunmitzera,'' and ''Heritiera. Papuan mahogany ''
Xylocarpus granatum
''Xylocarpus granatum'', commonly known as the cannonball mangrove, cedar mangrove, or puzzlenut tree, is a species of mangrove in the mahogany family (Meliaceae). It is found in Africa, Asia, Australasia and the Pacific Islands. It is a common ...
'' can form monotypic stands, reaching up to 20 meters in height, with buttressed trunks up to a meter across.
Where freshwater flows create a less salty
brackish
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estua ...
environment the mangrove palm ''
Nypa fruticans
''Nypa fruticans'', commonly known as the nipa palm (or simply nipa, from ms, nipah) or mangrove palm, is a species of palm native to the coastlines and estuarine habitats of the Indian and Pacific Oceans. It is the only palm considered adap ...
'' is common, together with ''
Xylocarpus granatum
''Xylocarpus granatum'', commonly known as the cannonball mangrove, cedar mangrove, or puzzlenut tree, is a species of mangrove in the mahogany family (Meliaceae). It is found in Africa, Asia, Australasia and the Pacific Islands. It is a common ...
'' and ''
Heritiera littoralis
''Heritiera littoralis'', commonly known as the looking-glass mangrove or tulip mangrove, is a mangrove tree in the family Malvaceae native to coastal areas of eastern Africa, Asia, Melanesia and northern Australia. The common name refers to the ...
Bruguiera sexangula
''Bruguiera sexangula'', commonly called the upriver orange mangrove, is a mangrove shrub or tree usually growing up to 15 m, occasionally 30 m, in height.
Description
''Bruguiera sexangula'' may grow as a single-stemmed tree or multi- ...
'', ''
Camptostemon schultzii
''Camptostemon'' is a genus of flowering plants belonging to the family Malvaceae.
Its native range is Central Malesia, Northern Australia.
Species:
*''Camptostemon aruensis''
*''Camptostemon philippinensis
''Camptostemon'' is a genus of ...
Heritiera littoralis
''Heritiera littoralis'', commonly known as the looking-glass mangrove or tulip mangrove, is a mangrove tree in the family Malvaceae native to coastal areas of eastern Africa, Asia, Melanesia and northern Australia. The common name refers to the ...
Xylocarpus granatum
''Xylocarpus granatum'', commonly known as the cannonball mangrove, cedar mangrove, or puzzlenut tree, is a species of mangrove in the mahogany family (Meliaceae). It is found in Africa, Asia, Australasia and the Pacific Islands. It is a common ...
'', along with typical freshwater swamp forest species, such as ''
Calophyllum
''Calophyllum'' is a genus of tropical flowering plants in the family Calophyllaceae. They are mainly distributed in Asia, with some species in Africa, the Americas, Australasia, and the Pacific Islands.
History
Members of the genus ''Calophyllu ...
'' spp., Kwila (''
Intsia bijuga
''Intsia bijuga'', commonly known as Borneo teak, Johnstone River teak, Kwila, Moluccan ironwood, Pacific teak, scrub mahogany and vesi, is a species of flowering tree in the family Fabaceae, native to the Indo-Pacific. It ranges from Tanzania ...
These continuously changing woodlands do not have a great variety of mammals, although the
greater sheath-tailed bat
The greater sheath-tailed bat or New Guinea sheath-tailed bat (''Emballonura furax'') is a species of sac-winged bat in the family Emballonuridae
Emballonuridae is a family of microbats, many of which are referred to as sac-winged or sheath-t ...
(''Emballonura furax'') is a near-endemic. Many species of birds also inhabit these forests including the
New Guinea flightless rail
The New Guinea flightless rail (''Megacrex inepta''), also known as the Papuan flightless rail, is a species of bird in the family Rallidae, in the monotypic genus ''Megacrex''. Sometimes however, it was included in ''Amaurornis'' or ''Habropt ...
western crowned pigeon
The western crowned pigeon (''Goura cristata''), also known as the common crowned pigeon or blue crowned pigeon, is a large, blue-grey pigeon with blue lacy crests over the head and dark blue mask feathers around its eyes. Both sexes are almost s ...
white-bellied pitohui
The white-bellied pitohui (''Pseudorectes incertus'') is a species of bird in the family Pachycephalidae.
It is found throughout the lowlands of southern New Guinea (Lorentz River to upper Fly River.
Taxonomy and systematics
The white-bellied ...
Mangrove forests act as a "natural cleaner". For example, they intercept land-derived nutrients,
pollutants
A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like o ...
, and suspended matter before these contaminants reach deeper water. They also prevent coastal
erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...
by stabilizing sediments provide nursery and spawning areas for commercially important fish and provide stop over sites for organisms such as
migratory birds
Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding and wintering grounds. Many species of bird migrate. Migration carries high costs in predation and mortality, including from hunting b ...
, mammals, and fish.
Threats and preservation
Even though this thick forest is hard to penetrate about 35% of the mangrove forests have been lost in the past two decades. These losses exceed those for
tropical rain forests
Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equa ...
and
coral reefs
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
...
. Mangrove trees grow on a narrow strip between land and ocean in river systems, between the latitudes 25 degrees N and 30 degrees S, and the constant renewal of the trees relies on rivers bringing nutrients to the coast in regular seasonal patterns. The limited distribution of this ecosystem adds to the delicacy of it. Many global changes such as an increased rise in sea water is largely thought to be responsible for the destruction of these mangrove forests. A few other factors such as
mariculture
Mariculture or marine farming is a specialized branch of aquaculture (which includes freshwater aquaculture) involving the cultivation of marine organisms for food and other animal products, in enclosed sections of the open ocean ( offshore m ...
,
agriculture
Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
, and
urbanization
Urbanization (or urbanisation) refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. It is predominantly th ...
have also contributed to the recent loss of mangrove habitats. Mangroves provide humans with
shrimp
Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are ref ...
, fish, honey, lumber, and reptile skins. Without this tropical habitat, many of these products would be reduced in our market.
Threats to mangroves in Bintuni Bay and on Daru and Bobo (Bristow) Islands, Western Province, PNG, includes cutting for firewood and charcoal burning. Cutters travel by canoe up creeks into the interior of the mangrove forest and clear-fell large areas of trees which from the outside appear untouched. The timber is sold in the market on Daru, an island which is home to 10% of the Western Province population i.e. some 15,000 people including immigrants from Indonesian New Guinea (Papua). It is doubtful the mangrove forests can sustain this level of harvesting. Kwila (''
Intsia bijuga
''Intsia bijuga'', commonly known as Borneo teak, Johnstone River teak, Kwila, Moluccan ironwood, Pacific teak, scrub mahogany and vesi, is a species of flowering tree in the family Fabaceae, native to the Indo-Pacific. It ranges from Tanzania ...
'') and Papuan mahogany have more valuable timber and so are more vulnerable.
Many steps around the world are being taken in an effort to conserve mangrove forests from being completely wiped out. Some of these efforts include replanting of trees by local communities, and the development of sustainable use systems within a community. This practice includes using resources from mangroves that is at a rate in which the ecosystem can recover.Maikut, Diana. "Ecology of Mangroves." 04 Jun 2004 Web.12 Apr 2009. .
Meanwhile, there are four protected areas that include some coastal mangroves: Bintuni Bay Nature Reserve,
Lorentz National Park
Lorentz National Park is a national park located in Central Papua, Indonesia, in the southwest of western New Guinea. With an area of 25,056 km2 (9,674 mi2), it is the largest national park in Southeast Asia. In 1999 Lorentz was declare ...
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...