Mangrove forests, also called mangrove swamps, mangrove thickets or mangals, are productive
wetland
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...
s that occur in 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 o ...
s. Mangrove forests grow mainly at tropical and subtropical latitudes because
mangroves
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 ...
cannot withstand freezing temperatures. There are about 80 different species of mangroves, all of which grow in areas with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate.
[What is a mangrove forest?]
National Ocean Service, NOAA. Updated: 25 March 2021. Retrieved: 4 October 2021.
Many mangrove forests can be recognised by their dense tangle of prop roots that make the trees appear to be standing on stilts above the water. This tangle of roots allows the trees to handle the daily rise and fall of tides, which means that most mangroves get flooded at least twice per day. The roots slow the movement of tidal waters, causing sediments to settle out of the water and build up the muddy bottom. Mangrove forests stabilise the coastline, reducing erosion from
storm surges, currents, waves, and tides. The intricate root system of mangroves also makes these forests attractive to fish and other organisms seeking food and shelter from predators.
Mangrove forests live at the interface between the land, the ocean, and the atmosphere, and are centres for the flow of energy and matter between these systems. They have attracted much research interest because of the various ecological functions of the mangrove ecosystems, including runoff and flood prevention, storage and recycling of nutrients and wastes, cultivation and energy conversion. The forests are major
blue carbon
Blue Carbon refers to organic carbon that is captured and stored by the world's oceanic and coastal ecosystems, mostly by algae, seagrasses, macroalgae, mangroves, salt marshes and other plants in coastal wetlands. The term Blue Carbon was coined ...
systems, storing considerable amounts of carbon in
marine sediments, thus becoming important regulators of
climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
.
[ ]
Material was copied from this source, which is available under
Creative Commons Attribution 4.0 International License
Marine microorganisms
Marine microorganisms are defined by their habitat as microorganisms living in a marine environment, that is, in the saltwater of a sea or ocean or the brackish water of a coastal estuary. A microorganism (or microbe) is any microscopic livin ...
are key parts of these mangrove ecosystems. However, much remains to be discovered about how
mangrove microbiomes contribute to high ecosystem productivity and efficient cycling of elements.
Overview
There are about 80 different species of mangrove trees. All of these trees grow in areas with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate. Mangrove forests grow only at tropical and subtropical latitudes near the equator because they cannot withstand freezing temperatures. Many mangrove forests can be recognised by their dense tangle of
prop roots that make the trees appear to be standing on stilts above the water. This tangle of roots allows the trees to handle the daily rise and fall of tides, which means that most mangroves get flooded at least twice per day. The roots slow the movement of
tidal waters, causing sediments to settle out of the water and build up the muddy bottom. Mangrove forests stabilise the coastline, reducing erosion from storm surges, currents, waves, and tides. The intricate root system of mangroves makes these forests attractive to fishes and other organisms seeking food and shelter from predators.
[Mangroves are trees and shrubs that have adapted to life in a saltwater environment]
National Marine Sanctuaries, NOAA. Retrieved 18 November 2021.
The main contribution of mangroves to the larger ecosystem comes from
litter fall
Plant litter (also leaf litter, tree litter, soil litter, litterfall or duff) is dead plant material (such as leaf, leaves, Bark (botany), bark, Needle (botany), needles, twigs, and cladodes) that have fallen to the ground. This detritus or dead ...
from the trees, which is then decomposed by
primary consumers
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
. Bacteria and protozoans colonise the plant litter and break it down chemically into
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...
s, minerals, carbon dioxide, and
nitrogenous wastes.
The
intertidal
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 Marine habitat, habitats with var ...
existence to which these trees are adapted represents the major limitation to the number of species able to thrive in their habitat. High tide brings in salt water, and when the tide recedes, solar evaporation of the seawater in the soil leads to further increases in salinity. The return of tide can flush out these soils, bringing them back to salinity levels comparable to that of seawater.
At low tide, organisms are exposed to increases in temperature and reduced moisture before being then cooled and flooded by the tide. Thus, for a plant to survive in this environment, it must tolerate broad ranges of salinity, temperature, and moisture, as well as several other key environmental factors—thus only a select few species make up the mangrove tree community.
A mangrove swamp typically features only a small number of tree species. It is not uncommon for a mangrove forest in the Caribbean to feature only three or four tree species. For comparison, a
tropical rainforest
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 equatori ...
biome may contain thousands of tree species, but this is not to say mangrove forests lack diversity. Though the trees are few in species, the ecosystem that these trees create provides a
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
for a great variety of other species, including as many as 174 species of marine
megafauna
In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common threshold ...
.
![Mangrove ecosystem in the coastal intertidal zone](https://upload.wikimedia.org/wikipedia/commons/b/b1/Mangrove_ecosystem_in_the_coastal_intertidal_zone.png)
Mangrove plants require a number of physiological adaptations to overcome the problems of
low environmental oxygen levels, high
salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
, and frequent
tidal flooding
Tidal flooding, also known as sunny day flooding or nuisance flooding, is the temporary inundation of low-lying areas, especially streets, during exceptionally high tide events, such as at full and new moons. The highest tides of the year may b ...
. Each species has its own solutions to these problems; this may be the primary reason why, on some shorelines, mangrove tree species show distinct zonation. Small environmental variations within a mangal may lead to greatly differing methods for coping with the environment. Therefore, the mix of species is partly determined by the tolerances of individual species to physical conditions, such as tidal flooding and salinity, but may also be influenced by other factors, such as crabs preying on plant seedlings.
Once established, mangrove roots provide an
oyster
Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not al ...
habitat and slow water flow, thereby enhancing sediment deposition in areas where it is already occurring. The fine,
anoxic
The term anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts:
* Anoxic waters, sea water, fresh water or groundwater that are depleted of diss ...
sediments under mangroves act as sinks for a variety of
heavy (trace) metals which
colloidal particle
Particle size is a notion introduced for comparing dimensions of solid particles ('' flecks''), liquid particles (''droplets''), or gaseous particles ('' bubbles''). The notion of particle size applies to particles in colloids, in ecology, in gr ...
s in the sediments have concentrated from the water. Mangrove removal disturbs these underlying sediments, often creating problems of trace metal contamination of seawater and organisms of the area.
Mangrove swamps protect coastal areas from
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 distin ...
,
storm surge
A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the n ...
(especially during
tropical cyclone
A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
s), and
tsunami
A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...
s.
They limit high-energy wave erosion mainly during events such as storm surges and tsunamis. The mangroves' massive root systems are efficient at dissipating wave energy.
Likewise, they slow down tidal water enough so that its sediment is deposited as the tide comes in, leaving all except fine particles when the tide ebbs. In this way, mangroves build their environments.
Because of the uniqueness of mangrove ecosystems and the protection against erosion they provide, they are often the object of conservation programs,
including national
biodiversity action plans.
Distribution
![Karte-Biom-Mangrove](https://upload.wikimedia.org/wikipedia/commons/c/cc/Karte-Biom-Mangrove.png)
Worldwide there are about 80 described species of mangroves that live along marine coasts. About 60 of these species are true mangroves which live only in the intertidal zone between high and low tides.
"Mangroves once covered three-quarters of the world's tropical coastlines, with Southeast Asia hosting the greatest diversity. Only 12 species live in the Americas. Mangroves range in size from small bushes to the 60-meter giants found in Ecuador. Within a given mangrove forest, different species occupy distinct niches. Those that can handle tidal soakings grow in the open sea, in sheltered bays, and on fringe islands. Trees adapted to drier, less salty soil can be found farther from the shoreline. Some mangroves flourish along riverbanks far inland, as long as the freshwater current is met by ocean tides."
[What's a Mangrove? And How Does It Work?]
''American Museum of Natural History''. Accessed 8 November 2021.
![Map Halophytes](https://upload.wikimedia.org/wikipedia/commons/c/c2/Map_Halophytes.png)
Mangroves can be found in over one hundred countries and territories in the tropical and subtropical regions of the world. The largest percentage of mangroves is found between the 5° N and 5° S latitudes. Approximately 75% of world's mangroves are found in just 15 countries.
Estimates of mangrove area based on remote sensing and global data tend to be lower than estimates based on literature and surveys for comparable periods.
In 2018, the Global Mangrove Watch Initiative released a global baseline based on remote sensing and global data for 2010. They estimated the total mangrove forest area of the world as of 2010 at , spanning 118 countries and territories.
Following the conventions for identifying geographic regions from the
Ramsar Convention
The Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat is an international treaty for the conservation and sustainable use of Ramsar sites (wetlands). It is also known as the Convention on Wetlands. It i ...
on Wetlands, researchers reported that Asia has the largest share (38.7%) of the world's mangroves, followed by Latin America and the Caribbean (20.3%), Africa (20.0%),
Oceania
Oceania (, , ) is a region, geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern Hemisphere, Eastern and Western Hemisphere, Western hemispheres, Oceania is estimated to have a land area of ...
(11.9%), and Northern America (8.4%).
Sundarbans
The largest mangrove forest in the world is in the
Sundarbans
Sundarbans (pronounced ) is a mangrove area in the delta formed by the confluence of the Padma, Brahmaputra and Meghna Rivers in the Bay of Bengal. It spans the area from the Baleswar River in Bangladesh's division of Khulna to the Hooghly R ...
. The Sundarban forest lies in the vast delta on the
Bay of Bengal
The Bay of Bengal is the northeastern part of the Indian Ocean, bounded on the west and northwest by India, on the north by Bangladesh, and on the east by Myanmar and the Andaman and Nicobar Islands of India. Its southern limit is a line between ...
formed by the super confluence of the
Brahmaputra
The Brahmaputra is a trans-boundary river which flows through Tibet, northeast India, and Bangladesh. It is also known as the Yarlung Tsangpo in Tibetan, the Siang/Dihang River in Arunachali, Luit in Assamese, and Jamuna River in Bangla. It ...
and
Meghna
The Meghna River ( bn, মেঘনা নদী) is one of the major rivers in Bangladesh, one of the three that form the Ganges Delta, the largest delta on earth, which fans out to the Bay of Bengal. A part of the Surma-Meghna River System, ...
rivers with distributaries of the
Ganges
The Ganges ( ) (in India: Ganga ( ); in Bangladesh: Padma ( )). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international river to which India, Bangladesh, Nepal and China are the riparian states." is ...
. The seasonally flooded
Sundarbans freshwater swamp forests lie inland from the mangrove forests on the coastal fringe. The forest covers of which about are in Bangladesh.
The Sundarbans is intersected by a complex network of tidal waterways,
mudflat
Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal fl ...
s and small islands of salt-tolerant mangrove forests. The interconnected network of waterways makes almost every portion of the forest accessible by boat. The area is known as an important habitat for the endangered
Bengal tiger
The Bengal tiger is a population of the ''Panthera tigris tigris'' subspecies. It ranks among the biggest wild cats alive today. It is considered to belong to the world's charismatic megafauna.
The tiger is estimated to have been present in ...
, as well as numerous fauna including species of birds,
spotted deer
The chital or cheetal (''Axis axis''; ), also known as the spotted deer, chital deer, and axis deer, is a deer species native to the Indian subcontinent. It was first described and given a binomial name by German naturalist Johann Christian Po ...
,
crocodile
Crocodiles (family (biology), family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to inclu ...
s and snakes. The fertile soils of the delta have been subject to intensive human use for centuries, and the ecoregion has been mostly converted to intensive agriculture, with few enclaves of forest remaining.
Additionally, the Sundarbans serves a crucial function as a protective barrier for millions of inhabitants against floods that result from
cyclone
In meteorology, a cyclone () is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above (opposite to an anti ...
s.
Four protected areas in the Sundarbans are listed as UNESCO
World Heritage Sites
A World Heritage Site is a landmark or area with legal protection by an international convention administered by the UNESCO, United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNES ...
. Despite these protections, the Indian Sundarbans were assessed as endangered in 2020 under the
IUCN Red List of Ecosystems
The IUCN Red List of Ecosystems (RLE) is a global framework for monitoring and documenting the status of ecosystems. It was developed by the International Union for Conservation of Nature for biodiversity risk assessment. Its main objectives are ...
framework. There is a consistent pattern of depleted biodiversity or loss of species and the ecological quality of the forest is declining.
File:সুন্দরবনের মানচিত্র.svg,
File:Royal Bengal Tiger in Sundarbans National Park.jpg,
File:20140402-IMG 4838.jpg, Channel in low tide
Ecosystem
The unique ecosystem found in the intricate mesh of mangrove roots offers a quiet marine habitat for young organisms.
In areas where roots are permanently submerged, the organisms they host include
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
,
barnacles,
oyster
Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not al ...
s,
sponges
Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through ...
, and
bryozoa
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a ...
, which all require a hard surface for anchoring while they filter-feed.
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 refer ...
and
mud lobsters use the muddy bottoms as their home.
Mangrove crab
Mangrove crabs are crabs that live among mangroves, and may belong to many different species and even families. They have been shown to be ecologically significant in many ways. They keep much of the energy within the forest by burying and cons ...
s eat the mangrove leaves, adding nutrients to the mangal mud for other bottom feeders. In at least some cases, the export of carbon fixed in mangroves is important in coastal food webs. Mangrove plantations host several commercially important species of fish and crustaceans.
In
Puerto Rico
Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...
, the
red
Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...
,
white
White is the lightest color and is achromatic (having no hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully reflect and scatter all the visible wavelengths of light. White on ...
, and
black
Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ...
mangroves occupy different ecological niches and have slightly different chemical compositions, so the carbon content varies between the species, as well between the different tissues of the plant (e.g., leaf matter versus roots).
There is a clear succession of these three trees from the lower elevations, which are dominated by red mangroves, to farther inland with a higher concentration of white mangroves.
Mangrove forests are an important part of the cycling and storage of carbon in tropical coastal ecosystems.
Knowing this, scientists seek to reconstruct the environment and investigate changes to the coastal ecosystem over thousands of years using sediment cores.
However, an additional complication is the imported marine organic matter that also gets deposited in the sediment through the tidal flushing of mangrove forests.
Mangrove forests can decay into
peat
Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...
deposits because of fungal and bacterial processes as well as by the action of
termite
Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blattode ...
s.
It becomes peat in good
geochemical, sedimentary, and
tectonic
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...
conditions.
The nature of these deposits depends on the environment and the types of mangroves involved. Termites process fallen leaf litter, root systems and wood from mangroves into peat to build their nests.
Termites stabilise the chemistry of this peat and represent approximately 2% of above ground carbon storage in mangroves.
As the nests are buried over time this carbon is stored in the sediment, and the carbon cycle continues.
Mangroves are an important source of
blue carbon
Blue Carbon refers to organic carbon that is captured and stored by the world's oceanic and coastal ecosystems, mostly by algae, seagrasses, macroalgae, mangroves, salt marshes and other plants in coastal wetlands. The term Blue Carbon was coined ...
. Globally, mangroves stored of carbon in 2012.
Two percent of global mangrove carbon was lost between 2000 and 2012, equivalent to a maximum potential of of
CO2 emissions.
Globally, mangroves have been shown to provide measurable economic protections to coastal communities affected by tropical storms.
Biodiversity
Birds
Heterogeneity
Homogeneity and heterogeneity are concepts often used in the sciences and statistics relating to the uniformity of a substance or organism. A material or image that is homogeneous is uniform in composition or character (i.e. color, shape, siz ...
in
landscape ecology
Landscape ecology is the science of studying and improving relationships between ecological processes in the environment and particular ecosystems. This is done within a variety of landscape scales, development spatial patterns, and organizati ...
is a measure of how different parts of a landscape are from one another. It can manifest in an ecosystem from the abiotic or biotic characteristics of the environment. For example, coastal mangrove forests are located at the land-sea interface, so their functioning is influenced by
abiotic factors
In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them und ...
such as tides, as well as biotic factors such as the extent and configuration of adjacent vegetation.
For forest birds, tidal inundation means that the availability of many mangrove resources fluctuates daily, suggesting foraging flexibility is likely to be important. Mangroves also offer estuarine prey items, such as mudskippers and crabs, that are not found in terrestrial forest types. Further, mangroves are often situated in a complex mosaic of adjacent vegetation types such as grasslands, saltmarshes, and woodlands, and this can mean that flexibility in foraging strategy and choice of foraging habitat may be advantageous for highly mobile forest birds.
[ ]
Material was copied from this source, which is available under
Creative Commons Attribution 4.0 International License
Relative to other forest types, mangroves support few bird species that are obligate habitat (mangrove) specialists and instead host many species with generalised foraging niches.
File:Mangrove Ecopark.jpg, Mangrove forests host many bird species with generalised foraging niches
File:Mangrove fantail, Rhipidura phasiana.jpg, Mangrove fantail
File: Mangrove Hummingbird ♂.jpg, Mangrove hummingbird
The mangrove hummingbird (''Amazilia boucardi'') is an Endangered species of hummingbird in the "emeralds", tribe Trochilini of subfamily Trochilinae. It is endemic to Costa Rica.
Taxonomy
The mangrove hummingbird was formally described in 18 ...
File:Collared kingfisher (Todiramphus chloris) - Flickr - Lip Kee.jpg, Mangrove kingfishers are found particularly in mangrove zones
File:Buteogallus anthracinus (8733195117).jpg, Mangrove black hawk
File:Young brown pelicans fishing.jpg, Brown pelican
The brown pelican (''Pelecanus occidentalis'') is a bird of the pelican family, Pelecanidae, one of three species found in the Americas and one of two that feed by diving into water. It is found on the Atlantic Coast from New Jersey to the mout ...
s fish and nest in mangrove forests
File:Little blue heron, Egretta caerulea.jpg, Little blue heron
The little blue heron (''Egretta caerulea'') is a small heron of the genus '' Egretta''. It is a small, darkly colored heron with a two-toned bill. Juveniles are entirely white, bearing resemblance to the snowy egret. During the breeding season ...
. The water is reflecting green mangrove trees.
File:Great egrets, Ardea alba, fishing.jpg, Three great egret
The great egret (''Ardea alba''), also known as the common egret, large egret, or (in the Old World) great white egret or great white heron is a large, widely distributed egret. The four subspecies are found in Asia, Africa, the Americas, and ...
s fishing along a mangrove shore
File:Pelicans and double breasted cormorants in the mangroves.jpg, Pelicans and cormorants high in the mangrove trees
;Bird sanctuaries
Mangrove forests are home and sanctuaries for many of
aquatic bird species, including:
*
Pulicat Lake Bird Sanctuary
Pulicat Lake Bird Sanctuary is a sanctuary for birds, 759 km2 in area, located in the Tirupati district of Andhra Pradesh and a protected area of the Thiruvallur District of Tamil Nadu, India. Pulicat Lake is the second largest brackish- ...
*
Mangalavanam Bird Sanctuary
Mangalavanam is an ecologically sensitive area situated at the centre of the Indian city of Kochi, covering about 2.74 hectares. It also houses a shallow tidal lake connected with Kochi backwaters by a canal. It is situated behind the Kerala High ...
*
Salim Ali Bird Sanctuary
*
Pichavaram
Pichavaram is a village near Chidambaram in Cuddalore District, Tamil Nadu, India. It is located between the Vellar estuary in the north and Coleroon estuary in the south. The Vellar-Coleroon estuarine complex forms the Killai backwater and t ...
*
Coringa Wildlife Sanctuary
Coringa Wildlife Sanctuary is an estuary situated near Kakinada in Andhra Pradesh, India.
It is the third largest stretch of mangrove forests in India with 24 mangrove tree species and more than 120 bird species. It is home to the critically ...
*
Sundarbans National Park
The Sundarbans National Park is a national park, tiger reserve and biosphere reserve in West Bengal, India. It is part of the Sundarbans on the Ganges Delta and adjacent to the Sundarban Reserve Forest in Bangladesh. It is located to south-w ...
Fish
The intricate root system of mangrove forests makes them attractive to adult fish seeking food and juvenile fish seeking shelter.
File:Jack Of The Mangroves - Flickr - tarotastic.jpg, Mangrove jack
The mangrove red snapper (''Lutjanus argentimaculatus''), also known as mangrove jack, grey snapper, creek red bream, Stuart evader, dog bream, purple sea perch, red bream, red perch, red reef bream, river roman, or rock barramundi, is a species ...
File:Mangrove snapper, Lutjanus griseus.jpg, Mangrove snapper
The mangrove snapper or gray snapper (''Lutjanus griseus'') is a species of snapper native to the western Atlantic Ocean from Massachusetts to Brazil, the Gulf of Mexico, Bermuda, and the Caribbean Sea. The species can be found in a wide varie ...
swimming among mangrove roots
File:School of Young Fishes (Atherina sp. ???) (6055617687).jpg, Old World silverside
The Old World silversides are a family, Atherinidae, of fish in the order Atheriniformes. Atherinidae are abundant and considered bony fish (teleost) that are widespread globally, living in rivers, estuaries, and coastal waters. They occur worldw ...
s schooling
A school is an educational institution designed to provide learning spaces and learning environments for the teaching of students under the direction of teachers. Most countries have systems of formal education, which is sometimes compuls ...
among mangrove roots
File:Barracuda among mangrove roots.jpg, Barracuda
A barracuda, or cuda for short, is a large, predatory, ray-finned fish known for its fearsome appearance and ferocious behaviour. The barracuda is a saltwater fish of the genus ''Sphyraena'', the only genus in the family Sphyraenidae, which was ...
lurks among mangrove root
File:Yellow seahorse in flooded mangrove forest.jpg, Yellow seahorses breed and give birth in Asia's flooded mangrove forests. Tangled roots and submerged branches offer shadowy shelter to pregnant dads and their offspring
File:Mudskipper - Surabaya mangroves - East Java (30019579862).jpg, Mudskippers can be found in mangrove swamps
File:Himantura granulata 2.jpg, Mangrove whipray
Mangrove crab holobiont
Mangrove forests are among the more productive and diverse ecosystems on the planet, despite limited
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
availability. Under such conditions, animal-microbe associations (
holobiont
A holobiont is an assemblage of a host and the many other species living in or around it, which together form a discrete ecological unit through symbiosis, though there is controversy over this discreteness. The components of a holobiont are in ...
s) are often key to ecosystem functioning. An example is the role of
fiddler crab
The fiddler crab or calling crab may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae, well known for their sexual dimorphism, sexually dimorphic claws; the males' major claw is much larger than th ...
s and their
carapace
A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
-associated microbial
biofilm
A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...
as hotspots of microbial nitrogen transformations and sources of nitrogen within the mangrove ecosystem.
Among coastal ecosystems, mangrove forests are of great importance as they account for three quarters of the tropical coastline and provide different ecosystem services. Mangrove ecosystems generally act as a net sink of carbon, although they release organic matter to the sea in the form of dissolved refractory macromolecules, leaves, branches and other debris.
In pristine environments, mangroves are among the most productive ecosystems on the planet, despite growing in tropical waters that are often nutrient depleted.
The refractory nature of the organic matter produced and retained in mangroves can slow the recycling of nutrients, particularly of nitrogen.
Nitrogen limitation in such systems may be overcome by microbial
nitrogen fixation
Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmo ...
when combined with high rates of
bioturbation
Bioturbation is defined as the reworking of soils and sediments by animals or plants. It includes burrowing, ingestion, and defecation of sediment grains. Bioturbating activities have a profound effect on the environment and are thought to be a pr ...
by macrofauna, such as crabs and lobsters.
Bioturbation by macrofauna affect nitrogen availability and multiple nitrogen related microbial processes through sediment reworking, burrow construction and
bioirrigation
Bioirrigation refers to the process of benthos, benthic organisms flushing their burrows with overlying water. The exchange of dissolved substances between the porewater and overlying seawater that results is an important process in the context o ...
, feeding and excretion. Macrofauna mix old and fresh organic matter, extend
oxic–anoxic sediment interfaces, increase the availability of energy-yielding
electron acceptors and increase nitrogen turnover via direct excretion. Thus, macrofauna may alleviate nitrogen limitation by priming the
remineralisation
In biogeochemistry, remineralisation (or remineralization) refers to the breakdown or transformation of organic matter (those molecules derived from a biological source) into its simplest inorganic forms. These transformations form a crucial link ...
of
refractory nitrogen
In materials science, a refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractories are polycrystalline, polyphase, ...
, reducing plant-microbe competition. Such activity ultimately promotes nitrogen recycling, plant assimilation and high nitrogen retention, as well as favours its loss by stimulating coupled
nitrification
''Nitrification'' is the biological oxidation of ammonia to nitrite followed by the oxidation of the nitrite to nitrate occurring through separate organisms or direct ammonia oxidation to nitrate in comammox bacteria. The transformation of amm ...
and
denitrification
Denitrification is a microbially facilitated process where nitrate (NO3−) is reduced and ultimately produces molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products. Facultative anaerobic bacteria perform denitr ...
.
![Thalassina anomala 2](https://upload.wikimedia.org/wikipedia/commons/a/a4/Thalassina_anomala_2.jpg)
Mangrove sediments are highly bioturbated by
decapods such as crabs.
Crab populations continuously rework sediment by constructing burrows, creating new niches, transporting or selectively grazing on sediment microbial communities.
In addition, crabs can affect organic matter turnover by assimilating leaves and producing finely fragmented faeces, or by carrying them into their burrows. Therefore, crabs are considered important ecosystem engineers shaping biogeochemical processes in intertidal muddy banks of mangroves. In contrast to burrowing polychaetes or amphipods, the abundant Ocipodid crabs, mainly represented by fiddler crabs, do not permanently ventilate their burrows. These crabs may temporarily leave their burrows for surface activities,
or otherwise plug their burrow entrance during tidal inundation in order to trap air. A recent study by Cuellar-Gempeler and Leibold
showed that these crabs can be associated with a diverse microbial community, either on their carapace or in their gut.
The exoskeleton of living animals, such as shells or carapaces, offers a habitat for microbial biofilms which are actively involved in different N-cycling pathways such as nitrification, denitrification and dissimilatory nitrate reduction to ammonium (DNRA). Colonizing the carapace of crabs may be advantageous for specific bacteria, because of host activities such as respiration, excretion, feeding and horizontal and vertical migrations. However, the ecological interactions between fiddler crabs and bacteria, their regulation and significance as well as their implications at scales spanning from the single individual to the ecosystem are not well understood.
File:Soldier crabs marching.jpg, Artist impression of small blue soldier crabs marching across a mangrove flat
File:Mangrove crab.jpg, Mangrove crab
Mangrove crabs are crabs that live among mangroves, and may belong to many different species and even families. They have been shown to be ecologically significant in many ways. They keep much of the energy within the forest by burying and cons ...
, possibly ''Neosarmatium asiaticum''
File:Mangrove tree crab, Aratus pisonii.jpg, Mangrove tree crab, '' Aratus pisonii''
Biogeochemistry
Carbon cycle
![Fate of mangrove primary production](https://upload.wikimedia.org/wikipedia/commons/3/3c/Fate_of_mangrove_primary_production.jpg)
Mangrove forests are amongst the world's most productive marine ecosystems,
with net primary productivity (NPP) in the order of 208 Tg C yr
−1.
Mangrove forests achieve a steady state once the forest reaches maximum biomass at around 20–30 years through a constant process of mortality and renewal
so, assuming the living biomass is not becoming more carbon dense, then carbon has to be lost at a rate equal to the amount of carbon fixed as NPP. Hence this productivity is either retained within the mangrove forest, as a standing stock of live material such as wood, buried in
sediments
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand a ...
, or exported to neighbouring habitats as litter,
particulate
Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM) or suspended particulate matter (SPM) – are microscopic particles of solid or liquid matter suspended in the air. The te ...
and
dissolved organic carbon
Dissolved organic carbon (DOC) is the fraction of organic carbon operationally defined as that which can pass through a filter with a pore size typically between 0.22 and 0.7 micrometers. The fraction remaining on the filter is called particu ...
(POC and DOC) and
dissolved inorganic carbon
Dissolved inorganic carbon (DIC) is the sum of the aqueous species of inorganic carbon in a solution. Carbon compounds can be distinguished as either organic or inorganic, and as dissolved or particulate, depending on their composition. Organic ...
(DIC), or lost to the atmosphere.
The out-welling hypothesis argues that export of locally derived POC and DOC is an important ecosystem function of mangroves, which drives detrital based
food webs
A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is consumer-resource system. Ecologists can broadly lump all life forms into one ...
in adjacent coastal habitats. Export of mangrove carbon has been estimated to make a significant trophic contribution to adjacent ecosystems. The theory of outwelling is supported by mass balance evaluations that show the amount of carbon fixed by mangroves normally greatly exceeds the amount stored within the forest,
although the scale of outwelling varies considerably between forests, due to differences in
coastal geomorphology, tidal regimes, freshwater flow and productivity.
![Pathways for the nitrogen cycle in mangrove forests](https://upload.wikimedia.org/wikipedia/commons/6/64/Pathways_for_the_nitrogen_cycle_in_mangrove_forests.webp)
In the 1990s, global estimates could account for 48% of the total global mangrove
primary production
In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through c ...
of 218 ± 72 million tons C yr
−1 (see diagram on the right). By incorporating information on carbon burial, efflux and carbon outwelled as leaf litter, POC and DOC, the remaining 52% was thought outwelled as DIC, though there was insufficient data to confirm this.
More recent assessments of DIC export at two sites in Australia
supported the estimates of Bouillon et al. in 2008,
although in 2014 Alongi suggested that only 40% of NPP was exported as DIC.
Nitrogen assimilation
Mangrove forests and coastal marshes are typically considered N-limited ecosystems because of their high primary production. Therefore, mangrove plants are highly efficient at utilising soil nitrogen, making them an important sink for excess nitrogen from upstream.
However, different mangrove species may still utilise nitrogen at different efficiencies, even though they share similar nitrogen pathways (see diagram on right). Reported nitrogen assimilation rates in mangrove plants ranged from 2 to 8 μmol g
−1 h
−1 under ambient nitrogen conditions, and 19 to 251 μmol g
−1 h
−1 when the nitrogen supply was unlimited.
In addition to species variation, different environmental conditions can also affect the nitrogen assimilation rates in mangrove plants. Because
Cl− ions can reduce
protein synthesis
Protein biosynthesis (or protein synthesis) is a core biological process, occurring inside Cell (biology), cells, homeostasis, balancing the loss of cellular proteins (via Proteolysis, degradation or Protein targeting, export) through the product ...
and
nitrogen assimilation Nitrogen assimilation is the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment. Organisms like plants, fungi and certain bacteria that can fix nitrogen gas (N2) depend on the abil ...
, soil
pore water
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
salinity appears to be a negative factor that significantly alters the nitrogen uptake rates of mangrove plants.
Exploitation and conservation
![Bali Barat mangroves](https://upload.wikimedia.org/wikipedia/commons/5/55/Bali_Barat_mangroves.jpg)
Adequate data is only available for about half of the global area of mangroves. However, of those areas for which data has been collected, it appears that 35% of the mangroves have been destroyed. Since the 1980s, around 2% of mangrove area is estimated to be lost each year. Assessments of global variation in mangrove loss indicates that national regulatory quality mediates how different drivers and pressures influence loss rates.
Shrimp farming
Shrimp farming is an aquaculture business that exists in either a marine or freshwater environment, producing shrimp or prawns (crustaceans of the groups Caridea or Dendrobranchiata) for human consumption.
Marine
Commercial marine shrimp farming ...
causes approximately a quarter of the destruction of mangrove forests. Likewise, the 2010 update of the World Mangrove Atlas indicated that approximately one fifth of the world's mangrove ecosystems have been lost since 1980,
although this rapid loss rate appears to have decreased since 2000 with global losses estimated at between 0.16% and 0.39% annually between 2000 and 2012.
Despite global loss rates decreasing since 2000, Southeast Asia remains an area of concern with loss rates between 3.6% and 8.1% between 2000 and 2012.
By far the most damaging form of shrimp farming is when a closed ponds system (non-
integrated multi-trophic aquaculture) is used, as these require destruction of a large part of the mangrove, and use antibiotics and disinfectants to suppress diseases that occur in this system, and which may also leak into the surrounding environment. Far less damage occurs when
integrated mangrove-shrimp aquaculture Integrated mangrove-shrimp (IMS) aquaculture is a sustainable farming system used as one of the measures for mangrove rehabilitation and can be described as a method of organic aquaculture. Silvoaquaculture or silvofisheries are also terms used to ...
is used, as this is connected to the sea and subjected to the tides, and less diseases occur, and as far less mangrove is destroyed for it.
Grassroots efforts to protect mangroves from development and from citizens cutting down the mangroves for
charcoal production,
cooking, heating and as a building material are becoming more popular.
Solar cooker
A solar cooker is a device which uses the energy of direct sunlight to heat, cook or pasteurize drink and other food materials. Many solar cookers currently in use are relatively inexpensive, low-tech devices, although some are as powerful or as ...
s are distributed by many non-government organizations as a low-cost alternative to wood and charcoal stoves. These may help in reducing the demand for charcoal.
* In Thailand, community management has been effective in restoring damaged mangroves. Also, production of mangrove
honey
Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...
is practiced, as a way to generate sustainable income for nearby people, keeping them from destroying the mangrove and generate a short-term revenue.
* In
Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
, honey is also produced in mangroves as a source of (non-destructive) income generation. In addition, silk pods from endemic silkworm species are also collected in the
Madagascar mangroves
Madagascar mangroves are a coastal ecoregion in the mangrove forest biome found on the west coast of Madagascar. They are included in the WWF's Global 200 list of most outstanding ecoregions.
Geography
Mangrove swamps are located in flat co ...
for
wild silk
Wild silks have been known and used in many countries from early times, although the scale of production is far smaller than that from cultivated silkworms. Silk cocoons and nests often resemble paper or cloth, and their use has arisen independent ...
production.
* In the
Bahamas
The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the Atlantic Ocean, North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to ...
, for example, active efforts to save mangroves are occurring on the islands of
Bimini
Bimini is the westernmost district of the Bahamas and comprises a chain of islands located about due east of Miami. Bimini is the closest point in the Bahamas to the mainland United States and approximately west-northwest of Nassau. The popula ...
and
Great Guana Cay
Great Guana Cay is an islet in The Bahamas. It is a long, narrow islet, long. It is in the centre of the Abaco Islands and is near Gumelemi Cay. It is about 8 miles from Marsh Harbour. Approximately 150 people live on the island, mostly along ...
.
* In
Trinidad and Tobago
Trinidad and Tobago (, ), officially the Republic of Trinidad and Tobago, is the southernmost island country in the Caribbean. Consisting of the main islands Trinidad and Tobago, and numerous much smaller islands, it is situated south of ...
as well, efforts are underway to protect a mangrove threatened by the construction of a steel mill and a port.
* Within northern Ecuador, mangrove regrowth is reported in almost all estuaries and stems primarily from local actors responding to earlier periods of deforestation in the Esmeraldas region.
[Hamilton, S. & S. Collins (2013]
Las respuestas a los medios de subsistencia deforestación de los manglares en las provincias del norte de Ecuador
Bosque 34:2
Mangroves have been reported to be able to help buffer against tsunami, cyclones, and other storms, and as such may be considered a flagship system for
ecosystem-based adaptation Ecosystem-based adaptation (EbA) encompasses a broad set of approaches to adapt to climate change. They all involve the management of ecosystems and their services to reduce the vulnerability of human communities to the impacts of climate change. ...
to the impacts of climate change. One village in
Tamil Nadu
Tamil Nadu (; , TN) is a States and union territories of India, state in southern India. It is the List of states and union territories of India by area, tenth largest Indian state by area and the List of states and union territories of India ...
was protected from tsunami destruction—the villagers in
Naluvedapathy planted 80,244 saplings to get into the
Guinness Book of World Records
''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a reference book published annually, listing world ...
. This created a kilometre-wide belt of trees of various varieties. When the
2004 tsunami struck, much of the land around the village was flooded, but the village suffered minimal damage.
Ocean deoxygenation
Compared to
seagrass meadow
A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and ...
s and
coral reef
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.
Co ...
s,
hypoxia is more common on a regular basis in mangrove ecosystems, through
ocean deoxygenation
Ocean deoxygenation is the reduction of the oxygen content of the global oceans and coastal zones due to human activities as a consequence of anthropogenic emissions of carbon dioxide and eutrophication-driven excess production. It is manifest ...
is compounding the negative effects by anthropogenic nutrient inputs and land use modification.
[Laffoley, D. & Baxter, J.M. (eds.) (2019)]
Ocean deoxygenation: Everyone's problem - Causes, impacts, consequences and solutions
IUCN, Switzerland.
Like seagrass, mangrove trees transport oxygen to roots of
rhizome
In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...
s, reduce sulfide concentrations, and alter microbial communities. Dissolved oxygen is more readily consumed in the interior of the mangrove forest. Anthropogenic inputs may push the limits of survival in many mangrove microhabitats. For example, shrimp ponds constructed in mangrove forests are considered the greatest anthropogenic threat to mangrove ecosystems. These shrimp ponds reduce
estuary
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...
circulation and water quality which leads to the promotion of
diel-cycling hypoxia. When the quality of the water degrades, the shrimp ponds are quickly abandoned leaving massive amounts of wastewater. This is a major source of water pollution that promotes ocean deoxygenation in the adjacent habitats.
Due to these frequent hypoxic conditions, the water does not provide habitats to fish. When exposed to extreme hypoxia, ecosystem function can completely collapse. Extreme deoxygenation will affect the local fish populations, which are an essential food source. The environmental costs of shrimp farms in the mangrove forests grossly outweigh the economic benefits of them. Cessation of shrimp production and restoration of these areas reduce eutrophication and anthropogenic hypoxia.
Reforestation
![Karachi Mangroves](https://upload.wikimedia.org/wikipedia/commons/4/44/Karachi_Mangroves.jpg)
In some areas, mangrove
reforestation
Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forests and woodlands (forestation) that have been depleted, usually through deforestation, but also after clearcutting.
Management
A debate ...
and
mangrove restoration
Mangrove restoration is the regeneration of mangrove forest ecosystems in areas where they have previously existed. The practice of mangrove restoration is grounded in the discipline of restoration ecology, which aims to “ ssistthe recovery of ...
is also underway. Red mangroves are the most common choice for cultivation, used particularly in
marine aquariums in a
sump
A sump is a low space that collects often undesirable liquids such as water or chemicals. A sump can also be an infiltration basin used to manage surface runoff water and recharge underground aquifers. Sump can also refer to an area in a cave ...
to reduce
nitrates
Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble ...
and other
nutrients
A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
in the water. Mangroves also appear in home
aquariums
An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, a ...
, and as ornamental plants, such as in
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
.
The Manzanar Mangrove Initiative is an ongoing experiment in
Arkiko
Arkiko ( ar, حرقيقو, Afar and Saho: ''Hirg-Higo'', alternately Archigo, Arqiqo, Ercoco, Hirgigo, Hargigo or Harkiko) is a town in the Northern Red Sea region of Eritrea. Situated on the Red Sea, it lies on the mainland across from the city ...
,
Eritrea
Eritrea ( ; ti, ኤርትራ, Ertra, ; ar, إرتريا, ʾIritriyā), officially the State of Eritrea, is a country in the Horn of Africa region of Eastern Africa, with its capital and largest city at Asmara. It is bordered by Ethiopia ...
, part of the Manzanar Project founded by
Gordon H. Sato, establishing new mangrove plantations on the coastal
mudflat
Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal fl ...
s. Initial plantings failed, but observation of the areas where mangroves did survive by themselves led to the conclusion that nutrients in water flow from inland were important to the health of the mangroves. Trials with the Eritrean Ministry of Fisheries followed, and a planting system was designed to provide the nitrogen, phosphorus, and iron missing from seawater.
The propagules are planted inside a reused galvanized steel can with the bottom knocked out; a small piece of iron and a pierced plastic bag with fertilizer containing nitrogen and phosphorus are buried with the propagule. , after six years of planting, 700,000 mangroves are growing; providing stock feed for sheep and habitat for oysters, crabs, other bivalves, and fish.
Another method of restoring mangroves is by using
quadcopters
A quadcopter or quadrotor is a type of helicopter with four rotors.
Although quadrotor helicopters and convertiplanes have long been flown experimentally, the configuration remained a curiosity until the arrival of the modern UAV or drone. T ...
(which are able to carry and deposit seed pods). According to Irina Fedorenko, an amount of work equivalent to weeks of planting using traditional methods can be done by a drone in days, and at a fraction of the cost.
Seventy percent of mangrove forests have been lost in
Java
Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...
,
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 Guine ...
. Mangroves formerly protected the island's coastal land from flooding and erosion.
[ ]Wetlands International
Wetlands International is a global organisation that works to sustain and restore wetlands and their resources for people and biodiversity. It is an independent, not-for-profit, global organisation, supported by government and NGO membership from ...
, an NGC based in the Netherlands, in collaboration with nine villages in Demak
Demak is on the north coast of Central Java province, on the island of Java, Indonesia.
* Demak, Demak, modern-day large town
* Demak Sultanate, sixteenth century sultanate
* Demak Regency
Demak ( jv, ꦢꦼꦩꦏ꧀) is a regency located in t ...
where lands and homes had been flooded, began reviving mangrove forests in Java. Wetlands International introduced the idea of developing tropical versions of techniques traditionally used by the Dutch to catch sediment in North Sea coastal salt marshes. Originally, the villagers constructed a sea barrier by hammering two rows of vertical bamboo poles into the seabed and filling the gaps with brushwood held in place with netting. Later the bamboo was replaced by PVC pipes filled with concrete. As sediment gets deposited around the brushwood, it serves to catch floating mangrove seeds and provide them with a stable base to germinate, take root and regrow. This creates a green belt of protection around the islands. As the mangroves mature, more sediment is held in the catchment area; the process is repeated until a mangrove forest has been restored. Eventually the protective structures will not be needed.[ By late 2018, of brushwood barriers along the coastline had been completed.][
A concern over reforestation is that although it supports increases in mangrove area it may actually result in a decrease in global mangrove functionality and poor restoration processes may result in longer term depletion of the mangrove resource.
]
National and international studies
In terms of local and national studies of mangrove loss, the case of Belize's mangroves is illustrative in its contrast to the global picture. A recent, satellite-based study—funded by the World Wildlife Fund and conducted by the Water Center for the Humid Tropics of Latin America and the Caribbean (CATHALAC)—indicates Belize's mangrove cover declined by a mere 2% over a 30-year period. The study was born out of the need to verify the popular conception that mangrove clearing in Belize was rampant.
Instead, the assessment showed, between 1980 and 2010, under of mangroves had been cleared, although clearing of mangroves near Belize's main coastal settlements (e.g. Belize City
Belize City is the largest city in Belize and was once the capital of the former British Honduras. According to the 2010 census, Belize City has a population of 57,169 people in 16,162 households. It is at the mouth of the Haulover Creek, wh ...
and San Pedro) was relatively high. The rate of loss of Belize's mangroves—at 0.07% per year between 1980 and 2010—was much lower than Belize's overall rate of forest clearing (0.6% per year in the same period). These findings can also be interpreted to indicate Belize's mangrove regulations (under the nation's) have largely been effective. Nevertheless, the need to protect Belize's mangroves is imperative, as a 2009 study by the World Resources Institute (WRI) indicates the ecosystems contribute to million per year to Belize's national economy.
In May 2019, ORNL DAAC News announced that NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
's Carbon Monitoring System (CMS), using new satellite-based maps of global mangrove forests across 116 countries, had created a new dataset to characterize the "distribution, biomass, and canopy height of mangrove-forested wetlands". Mangrove forests move carbon dioxide "from the atmosphere into long-term storage" in greater quantities than other forests, making them "among the planet's best carbon scrubbers" according to a NASA-led study.
See also
* Ecological values of mangroves
Mangrove ecosystems represent natural capital capable of producing a wide range of goods and services for coastal environments and communities and society as a whole. Some of these outputs, such as timber, are freely exchanged in formal markets. V ...
* Mangrove restoration
Mangrove restoration is the regeneration of mangrove forest ecosystems in areas where they have previously existed. The practice of mangrove restoration is grounded in the discipline of restoration ecology, which aims to “ ssistthe recovery of ...
* Mangrove tree distribution
Global mangrove distributions have fluctuated throughout human and geological history. The area covered by mangroves is influenced by a complex interaction between land position, rainfall hydrology, sea level, sedimentation, subsidence, storms an ...
* Freshwater swamp forest
Freshwater swamp forests, or flooded forests, are forests which are inundated with freshwater, either permanently or seasonally. They normally occur along the lower reaches of rivers and around freshwater lakes. Freshwater swamp forests are found ...
References
{{reflist