Wildlife of Sunderban

Wildlife diversity is not so high in Sunderban because of salinity. But exception is Royal Bangle Tiger and crocodile. There are also Deer, Monkey but birds and snakes are rare in Sunderban.

Crocodile, taking rest under the sun shine

A bird of Sundarban

A beautiful fish

Ecotourism in Sunderban

Sunderban is covered major beauty of Bangladesh. Tiger and deer are the main attraction of Sunderban. It is so beautiful when you travel in a narrow canal by the boat. For these there is a lot of opportunity for ecotourism. There are a lot of attractive places in which we traveled such as Harbaria, Dublar chor, Alorcol, Kotka, Hiron point, Kochi khali and so on. We saw an over mature Keora plantation garden. Sunderban forest floor is not suitable for walking but that place is cleared and nude. There is no true succession in Sunderban. Because there is random selection for species growing. Sometime keora-baen-geowa-sundri is the flow of the species growing but it is not true at all in every place.

Boys and girls try to cross the river bank

Dispersal and establishment of propagules of Mangrove species

Most mangrove species have buoyant, water-borne propagules.

The dispersal of these propagules is constrained by land masses blocking current flow, and by wide bodies of water.

Such limitations on dispersal usually confines species to particular regions, depending on their dispersive range and their ability to become established in new locations. 

In order to establish new colonies and to extend existing distributional ranges, species would need to across or around either larger bodies of water or land.

The effective range of each species depends on a number of factors including:

•      The number of days propagules remain bouyant and viable

•      The rate of surface currents

•      The water conditions and

•      The availability of suitable habitats.

Flotation times of mangrove propagules, fruits and seeds vary from a few days to many months (e.g. Steinke, 1975, 1986; Rabinowitz, 1978).

Flotation time may also increase with decreased water temperature (Steinke & Naidoo, 1991) and decreased water salinity (e.g. Rabinowitz, 1978).

Affect of wind, ocean current, fresh water flow and salinity on Mangrove ecosystem

Wind, ocean current, fresh water flow and salinity have the strong influence on the establishment of mangrove ecosystem and also influence the growth and reproduction of mangroves.

Wind

Wind has influence on waves and currents in coastal areas cause soil erosion and changes in mangrove structure. Plants often depend on winds as agents of pollination and seed dissemination which affects biodiversity.

Ocean current

Ocean currents also vary considerably in rate and direction with climate, weather conditions, seasons, and annual changes.

Ocean current has influence on

¡  The mangrove establishment and its biodiversity.

¡  Mangrove deviations from tropical zone mostly correlate with warm and cold oceanic currents.

¡  The distributional ranges tend to be broader on eastern continental margins than on western coastlines.

¡  The occurrences of mangroves at Japan, 35 to 40^o south latitude at the east coast of Africa, Australia and New-Zeeland.

Fresh water flow and Salinity

Salinity and fresh water flow has considerable effect on mangrove establishment, distribution and species composition.

Influences of light, rainfall and temperature on Mangrove Ecosystem

Light, rainfall and temperature have the strong influence on the establishment of mangrove ecosystem and also influence the growth and reproduction of mangroves.

Light 

Mangrove plants are long day plants thus it requires high intensity with long duration of full sunlight. This makes tropical coastal zones an ideal habitat. The optimal range of light intensity for the growth of mangrove species is 3,000- 3,800 Kcal/m²/day.

Rainfall

The amount, duration and distribution of rainfall are important factors that determining the development and distribution of mangrove plants and animals.

ž  Rainfall affects other environmental factors in the mangroves such as

¡  Air and water temperature

¡  Salinity of surface and groundwater

¡  Ultimately affects the survival of mangrove species.

ž   Mangroves thrive in areas with a range of 1500-3000 mm of annual rainfall.

Temperature 

ž  Mangroves are restricted generally to areas where

o   Mean air temperatures of the coldest months are higher than 20°C, and

o   The seasonal range of temperature fluctuation does not exceed 10°C (Walsh, 1974; Chapman, 1975, 1977)

ž  Global distributions of mangroves are limited chiefly by the physiological tolerance of each species to low temperature.

o   For example: Viable propagules  of Rhizophora mangle from Mexico routinely reach at the beaches and estuaries of southern Texas.

o   Some propagules become established, but they usually killed during the freezing winter season (Sherrod, Hockday & McMillan, 1986).

Factors, affecting the distribution of Mangroves

Environmental factors known to influence the distribution of particular mangroves

·        Evaporation rate

·        Frequency of saltwater inundation

·        Hydrology (Tides, currents, sea level and wave action)

·        Geomorphology (Catchment size, Estuary length, Sediment types and Slope)

·        Exposure to freshwater

·        Land runoff

·        Groundwater seepage

·        Land use in the adjacent catchments

 E.g. Cleared catchments tend to have increased sediment runoff

·        Oxygen availability

 E.g. aerobic or anaerobic sediment

·        Nutrient availability and pH

·        Feeding on seeds

             E.g. crabs selectively eat the propagules of certain mangrove species.

Factors affecting the Sundarban

Factors affecting the Sundarbans mangrove forest as the single largest tract of mangrove forest in the world. 

¡  Low salinity

¡  High tidal amplitude

¡  Gentle slope of the forest floor

¡  low elevation of land

¡  Numerous network of rivers

¡  High load of sediments

¡  A high fresh water discharge

¡  Shallow continental shelf

¡  Protected shore

¡  Climate is favorable: tropical and sub-tropical

Fishing in Sundarban

Fisherman is catching fish in the river of Sundarban

Kotka sea beach

Kotka sea beach

Travelling in Sundarban

Boy lost his shoes in very silty soil of Sundarban

Tiger footprint in Sundarban

Tiger footprint in Sundarban

Beautiful sun set in the Mangrove forest Sunderban

Beautiful sun set in the mangrove forest Sundarban

Pneumetaphores of Sundri (Heritiera fomes)

Pneumetaphores of Sundri (Heritiera fomes)

River bank of Sundarban

River bank of Sundarban

Distribution of Mangrove forest

Only mangrove means some characteristically halophytic species but people take it as a forest. So if you want to talk about Mangrove forest; yes, it will be as 'Mangrove forest'.

Mangrove forest distribution in the world.

If you see the above map you find that almost all of mangrove forests are in the tropical and sub-tropical region of the world mainly between latitudes 25° N and 25° S. Rest of the mangrove forest areas of the earth was 53,190 square miles (137,760 km²) in 2000 and it covers 118 countries and territories.

Here we see some countries covered mangrove forest in below:

Country	Ecozone
Angola	Afrotropic
Australia	Australasian
Bahamas	Neotropic
Bangladesh	Indomalayan
Belize	Neotropic
Brazil	Neotropic
Brunei	Indomalayan
Burma	Indomalayan
Cambodia	Indomalayan
Cameroon	Afrotropic
Colombia	Neotropic
Costa Rica	Neotropic
Cuba	Neotropic
Democratic Republic of the Congo	Afrotropic
Dominican Republic	Neotropic
Ecuador	Neotropic
El Salvador	Neotropic
Equatorial Guinea	Afrotropic
French Guiana	Neotropic
Gabon	Afrotropic
Gambia	Afrotropic
Ghana	Afrotropic
Guatemala	Neotropic
Guinea	Afrotropic
Guinea-Bissau	Afrotropic
Guyana	Neotropic
Haiti	Neotropic
Honduras	Neotropic
India	Indomalayan
Indonesia	Indomalayan
Jamaica	Neotropic
Kenya	Afrotropic
Lesser Antilles (Caribbees)	Neotropic
Liberia	Afrotropic
Madagascar	Afrotropic
Malaysia	Indomalayan
Mexico	Neotropic
Mozambique	Afrotropic
New Zealand	Australasian
Nicaragua Ecuador	Neotropic
Nigeria	Afrotropic
Panama	Neotropic
Peru	Neotropic
Puerto Rico	Neotropic
Senegal	Afrotropic
Sierra Leone	Afrotropic
South Africa	Afrotropic
Suriname	Neotropic
Tanzania	Afrotropic
Thailand	Indomalayan
The Republic of Ivory Coast	Afrotropic
Trinidad and Tobago	Neotropic
Turks and Caicos Islands	Neotropic
United States	Neotropic
Venezuela	Neotropic
Vietnam	Indomalayan

Here ecozone is a term which means broadest biogeographic division of earth.

Can mangroves provide protection from natural calamities?

It is a false imagination that mangrove forest protect coastal area from natural disaster like cyclone, storm, etc. But this idea is completely false rather mangrove grows or built up in a sheltered region. Special characteristics of mangrove species is small root, does not go in deep soil, comparably middle aged and height species from other forest. So Mangrove species are weak to protect itself from Sidor, Ayla etc cyclone. If you observe the wind direction in the ocean heavy wind does not pass over the mangrove forest.