Biology of MANGROVE

1
Biology of MANGROVE
Mujizat Kawaroe Marine Biology and Biodiversity
LaboratoryDepartment of Marine Science and
TechnologyBOGOR AGRICULTURAL UNIVERSITY
2
Mangrove

• The Shorter Oxford Dictionary describe the word
  "mangrove" as obscurely connected with the
  Portuguese word "mangue" and the Spanish word
  "mangle" and the English word "grove" and it
  dates its origin as 1613.
• Marta Vannucci in her  book "The Mangrove and Us"
  points out that the word is neither Portuguese
  nor Spanish and, after an exhaustive search, she
  concludes that the word "mangue" derives from the
  national language of Senegal. She comments that
  it was probably adopted by the Portuguese, and
  later modified by the Spanish, as a result of
  their exploration of the coast of West Africa.  

3
Mangrove

• The term "mangrove" has been applied historically
  to plants which live in muddy, sand, wet soil in
  tropical or subtropical tidal waters.
• In the nineteen sixties the term "mangal" was
  used for a community of mangrove plants and the
  term "mangrove" for the plant species making up
  the forest.
• The terminology has tended to fall into disuse
  recently and term such as "mangrove forest",
  "tidal forest" and "coastal woodland" have begun
  to appear from groups of evergreen plants
  possessing marked similarities in their
  physiological characteristics and structural
  adaptations to habitats influenced by the tides.
• The scientific literature is divided broadly into
  studies of the biology of individual species of
  plants or animals in the mangroves and the study
  of communities that may involve just plants or
  the relationship between plants and animals.
• The present intention is to sketch the most
  important features of mangroves and mangrove
  communities in such a way that they can be
  understood by the interested user.  

4
Mangrove

• Mangroves can be trees, shrubs, palms or ground
  ferns growing in the zone between high and low
  tide. Every kind of plant has a Latin name or
  latinised scientific name and mangroves are no
  exception.  
• The Swedish naturalist, Carl von Linne (Linnaeus)
  in 1735 devised a system for classifying plants
  and animals in systematic way. Linnaeus assigned
  each different kind of organism a latinised
  double name consisting of a genus name followed
  by an exclusive species name. This system is
  known as binomial nomenclature.  
• The classification of plants divides them into
  various categories, based on increasing degree of
  similarity. The largest categories are division,
  which are subdivided into classes, order,
  families, and genera. Each genus may contain only
  a single species or many closely related species.
  Biological species are physically and genetically
  similar to the extent they may interbreed to
  produce viable offspring.  

5
Mangrove

• There are approximately 70 species of true
  mangroves of which some 65 contribute
  significantly to the structure of mangrove
  forests. Approximately 15 species occur in
  South-East Asia, approximately 15 species occur
  in Africa, and approximately 10 species occur in
  the America.  
• There are nineteen plant families with mangrove
  representatives and only two families which are
  exclusively mangrove.
• There are no order or higher ranks that are
  exclusively mangroves. Mangroves are not a single
  genetic group but represent genetic adaptation of
  a large variety of plant families to a particular
  environment.
• In case of plant family, Rhizophoraceae, often
  considered to be a true mangrove family, only
  four of its 16 genera inhabit a mangrove
  habitat.   

6
Mangrove

• Extensive mangrove stands require a layer of
  earth or sand, usually deposited by rivers and
  flood tides and shores free of strong wave and
  tidal action. The also require salt and brackish
  water.
• Mangroves are often characterized by aerial
  roots, seedling that germinate on the tree and
  buoyant seeds that can be dispersed by water.
• Mangroves are often found in regions such as
  estuaries, embayments and broad muddy tidal flats
  where the local terrain has led to the build up
  of soil.
• They prefer sheltered places where tidal and wind
  are not too destructive. The conditions in which
  mangroves grow also influence their
  characteristics for survival, their size and the
  pattern in which they congregate.
• On a global scale mangrove distribution is
  influenced by the presence of warm and cold
  oceanic currents.  

7
Tidal Inundation

• Mangroves are facultative halophytes which means
  salt water is not a physical requirement for
  growth. Most can grow well in fresh water, but
  mangrove communities are not usually found in
  strict freshwater environments.
• There are two possible explanations. Most strict
  freshwater habitats exist where tidal inundation
  does not occur. Although not a direct physical
  requirement, tidal fluctuation plays an important
  indirect role in mangrove distribution.
• Tidal fluctuation results in the reduction of
  competition due to alternating wetting and
  drying, transportation of relatively clean water
  and nutrients in, exporting wastes, detritus, and
  sulfur compounds, effective dispersal of
  propagules. Where evaporation is very high, tidal
  fluctuation wash excess salt away preventing
  excessively high soil salinity concentrations.
  Due to the above factors, mangrove systems reach
  greatest development around the world in
  low-lying regions with relatively large tidal
  fluctuations. In Red mangroves,prop roots extend
  above most high tide levels. Black mangroves are
  excluded as water depths increase. In freshwater
  communities other species may out compete the
  mangroves for space.

8
Mangrove Forest

• Mangrove forests are best developed on tropical
  shorelines where there are large areas available
  between high and low tide points. Large mangrove
  formation are typically found in sheltered muddy
  shorelines that are often associated with the
  formation of deltas at the mouth of a river
  system. Mangroves can also be found growing on
  sandy and rocky shores, coral reefs and oceanic
  islands. There are instances where islands can be
  completely covered by mangroves. It is impossible
  to describe a typical mangrove forest, as the
  variation in height and girth, even for the same
  species, is immense, depending on the many
  factors that control growth  

9
Mineral elemen

• All plants require various mineral elements to
  survive and these are absorbed by the roots from
  the soil. Plants require nitrogen, phosphorus,
  potassium, calcium, magnesium, sulphur and iron.
  Sodium chlorides required only in trace
  quantities and this poses certain problems for
  mangroves due to high abundance of these two
  elements in the sea water surrounding their
  roots. Other trace elements required by the
  plants for successful growth are boron,
  manganese, zinc, copper and molybdenum.  

10
Mangrove soil

• Mangrove soils are quite different from those
  that most other terrestrial plants grow on. They
  are poorly drained, lacking in oxygen and are
  often fine grained and rich in organic matter. In
  appearance the soils are often clayey mud or
  sand.  
• Mangroves grow on waterlogged soils that are
  often lacking in oxygen. These are known as
  anaerobic soils, literally, soil without air. The
  lack of oxygen in the soil is due to the slow
  rate of diffusion of oxygen in water and the
  biological activity of microorganisms in the soil
  which consumes oxygen. The amount of oxygen in
  the soil varies according to how often and for
  how long tides cover the mud, how well drained
  the areas are, and whether there are chemicals in
  the soil that absorb oxygen. Oxygen in the soil
  could be expected to increase in proportion to
  the amount of time that the soil is exposed to
  the air and the soil is covered by water. Extreme
  lack of oxygen in the soil can lead to the
  formation of gas, hydrogen sulphide, which has
  rotten egg smell often associated with mangrove
  swamps.  

11
The various functional types of mangrove forest

• Over wash mangrove forests exist as islands
  frequently washed over by tides. All species are
  present with the Red mangrove the dominant
  species. Typically, these islands develop as a
  Red mangrove propagule strands in a shallow flat.
  As the island develops the roots eventually trap
  sediment. Often, bare sand flats are found in the
  center of these islandsThe maximum height of the
  community is between 7 m. These are small islands
  covered with mangroves that are frequently washed
  by the tides. The dominant species is Rhizophora
  mangle or the red mangrove.  
• Fringing mangrove forests exist as a relatively
  thin fringe along waterways. These forests appear
  to be flushed daily by tides, but do not receive
  then amount of terrestrial runoff as the riverine
  forests. Typically, the classic mangrove zonation
  pattern of seaward Red-Black-landward White
  scheme is exhibited in this forest. Maximum
  heights of trees in this community are slightly
  over l0 m. These strips of mangrove found along
  waterways and covered by daily tides. The
  dominant species is Rhizophora mangle.  

12
The various functional types of mangrove forest

• Riverine mangrove forests are tall flood plain
  forests along flowing waters such as tidal rivers
  and creeks. Conditions are favorable for
  extensive growth due to flushing by daily tides.
  In addition, freshwater runoff and terrestrial
  nutrient influx enhance this type of mangrove
  community. Maximum heights of trees in this
  community are 66 feet (20 m). These are luxuriant
  stands of mangrove along tidal rivers and creek
  with a good input of fresh water. Often composed
  of Rhizophora, Avicennia.  
• Basin mangrove forests are inland in
  depressions channeling terrestrial runoff toward
  the coast. Trees in this community have maximum
  heights of almost l5 m. These are stunted
  mangroves located in places such as the interior
  of swamps. Often dominated by Avicennia.  
• Hammock mangrove forests are in depressions but
  exist on slightly elevated ground. Trees rarely
  growth height in excess of 5 m. Tidal flushing of
  both of the communities is infrequent. Similar to
  basin mangrove forests but are found in more
  elevated sites.  
• Scrub mangrove forest are common in the flat
  coastal fringe of southern Florida and the Keys.
  All 3 species are present, but height is limited
  to less than l.5-2 m except in depressions of
  mangrove peat. Nutrients appear to be the
  limiting factors affecting growth, although
  substrate (marl) is also important. A dwarfed
  stand of mangroves found on flat coastal
  fringes.  

13
Mangrove animal

• The mangrove forest is transitional between land
  and sea, the animals that live there can come
  from either  environment.
• The mangrove animals live in a variety of
  habitats which can range from within or on the
  surface  of the mud, through the creeks, channels
  and pools, to the tree roots, trunk and canopy.
• The tidal cycle exercises a profound influence
  over the behavior and activity of marine animals
  in the mangrove.
• Large mangrove animals living on the surface of
  the mud, which is exposed at low tides, are
  almost always protected  from drying out by a
  shell or some hard supporting structure.

14
Fishes, shell fishes and crustaceans   

• Major constituents of this group in the mangrove
  environment of species of fishes, species of 
  shell fished and species of crustaceans. 
• Commercially important are Meretrix  sp.,
  Crassostrea sp., Penaeus sp., Scylla serrata and
  Mugil cephalis  
• Many crustaceans in the mangroves make burrows
  which are used for refuge, the feeding, as a
  source of water or for establishing a territory
  necessary for mating.
• Some may filter water through their burrows,
  feeding on suspended detritus and plankton while
  others may breed there. These burrows play and
  important role in the mangroves, aerating,
  draining and turning the dense waterlogged soil -
  a direct benefit to the plants which in turn give
  them shelter. 
• There is a limit to how many burrows can be dug
  in any one area. It seems that when there are too
  many, homeless crabs may try to take over
  occupied ones. Some fiddler crabs and ghost crabs
  have been observed filing in the burrows of their
  neighbors to maintain their territories

15

• Scylla serrata, the large edible swimming crab,
  inhabits the muddy bottom of mangrove estuaries,
  as well as  coastal brackish water.
• Thalassina anomala, the mud lobster is also found
  along estuaries and tidal rivers.  They build
  long tunneling burrows that can reach up to four
  meters in length and can be recognized by 
  spectacular turrets of earth rising to two meters
  in height above the surface.  
• Mud skippers are one of the fish which live  on
  the mud flats associated with mangroves shores.
  The mud skipper is a fish well adapted to
  alternating period of exposure to air and
  submersion and is frequently seen  hopping along
  the mud at the water's edge. They are
  well-comouflaged and able to change colour to
  match their background. It respires under water
  like other fish but out of the water gulp air.
  When submerged it swims like a fish but on land
  proceeds by a series of skips. Some of them can
  even climb  trees using their fused pelvic (rear)
  fins as suckers and their pectoral fins as
  grasping 'arms'. When a mud skippers is out of
  water it carries in its expanded gill chamber a
  reserve from which to extract oxygen. After a few
  minutes, when this reserve is exhausted, it is
  replenished from pool or from water in the
  burrows which they dig. The mud skipper's most
  noticeable feature is a pair of highly mobile
  eyes perched on top of the head to  increase the
  field of view and to enable it to see both under
  and over the water.  

16

• Birds are a prominent part of most mangrove
  forests and they are often present in large
  numbers. The  mangrove habitats offer rich
  feeding grounds for many of the large and  more
  spectacular species as well as a  multitude of
  small birds. About 177 species of resident and
  migratory birds are found in the mangrove
  forests. The most common among these are
  Kingfishers, herons, storks, sea eagles, kites,
  sand pipers, Curlews, terens etc. Flamingoes
  flock the exposed mud flats, during the low
  tides. They use mangrove environs as  breeding
  and feeding grounds.  
•  A great deal of wildlife diversity is found in
  the mangrove forests of India. The Royal Bengal
  Tiger is one of the  unique resident species of
  mangroves of the Sunderbans.  Reptiles are also
  common in  mangroves and can  include snakes,
  turtles, crocodiles and alligators. The salt
  water crocodile, commonly found in mangroves, has
  adapted so well to salt water conditions that it
  can survive indefinitely in a range of salinity's
  and appear to  have functional salt glands on its
  tongue. Monitor lizard  (Varanus sp.), estuarine
  crocodile, various species of  monkeys, otters,
  deer's, fishing cats and wild pigs are some of
  the most common species of mangrove forests  of
  India.