The Sundarbans: A Gift to Bengal

The Sundarbans, the world's largest contiguous mangrove forest, is located in the Ganges delta, which is created where the Padma, Brahmaputra, and Meghna rivers meet in the Bay of Bengal. This region is intersected by a complex network of tidal waterways or channels, mudflats, and mangrove forests. This mangrove ecosystem straddles the border between Bangladesh and India, stretching from the Baleswar River in Bangladesh's division of Khulna to the Hooghly River in India's state of West Bengal. The Sundarbans mangrove forest spans an area of around 10,000 km ² , of which the forests in Bangladesh's Khulna Division encompass 6,017 km ²  (60%) and those in West Bengal cover 4,260 km ²  (40%) throughout the South 24 Parganas and North 24 Parganas districts. The land area of the Sundarbans, including exposed sandbars, occupies 414,259 ha (70%), with water bodies covering 187,413 ha (30%). There have different opinions about the origin of the name of this mangrove forest. Such as, the predominant Sundari tree (Heritiera fomes) present there gave rise to the name Sundarbans. Another opinion is that it is derived from the word "Samunder Ban," which means "sea forests."The word "Sundar," which means "beautiful," may have also been a source, as the forest is beautiful to look at.

The Sundarbans are of exceptional scientific and biological interest and present unique possibilities for ecotourism, biological investigation, and environmental education. In the nature of a wildlife sanctuary, some regions of the forest have been designated as protected areas. These sites contain a significant concentration of wildlife and vegetation that has not been disturbed in decades. About five hundred years ago, it was realized that the forest was a significant source of resources. However, serious scientific management of the forest was started more than 120 years ago. This is highly important because mangroves are still not seen as a sustainable resource base in a number of Asian, African, and tropical Latin American countries. Therefore, the UNESCO World Heritage Committee, at its 21st session in 1997, included Bangladesh's Sundarbans in its list of World Heritage Sites due to its outstanding ecological importance. However, India's Sundarbans was also included as a World Heritage Site in 1987.

The Sundarbans features two ecoregions — "Sundarbans freshwater swamp forests" and "Sundarbans mangroves"

Sundarbans is the home of more than 300 species of plants, among them, some are true mangroves.

In 1903, Prain recorded the plants of swamp forest, grass-savannah, strand vegetation and reclaimed areas across the entire expanse of the Sundarban and identified a total of 334 species under 245 genera. Among the plant species are 18 euphorbias, 29 types of grasses, 19 sedges, and 35 legumes. The Sundarbans alone include 35 of the 50 true mangrove plant species that have been identified all over the world.

The dominant floral species in the Sundarban is Sundri - a member of the Sterculiaceae family.

Assemblage of species typical to the Sundarban once extended from the coast of Orissa through the Sundarban, Chakaria, and the Naf estuary in Bangladesh to Tanasserim and in the Irrawaddy delta in Myanmar.

In the Sundarban, three distinct vegetation types have been documented concerning varying degrees of water salinity and freshwater flow.

The primary plant types in the northeast, where freshwater flow is currently at its peak, are Sundri, either in isolated patches or mixed with Gewa, Passur (Xylocarpus mekongensis), and Kankra (Bruguiere gymnorrhiza). Some areas of Sundri and Gewa are connected to the discontinuous presence of Dhundal (Xylocarpus granatum) and Kankra. The Goran grows in drier areas, whereas the Shingra (Cynometra ramiflora) and Amur (Amoora cucullata) do so in more saturated soils as ground cover plants. Golpata is abundant among the recently developed mudflats along the riverbanks and drainage streams of the Sundarbans.

Gewa is the predominate woody species in the southern region near the sea, which clearly has the highest seasonal salinity change. In the back swamps, which are frequently submerged by the tide twice daily, Gewa is frequently mingled with the Sundri. It is frequently linked to the Passur and occasionally the Goran's thick understory. The Keora generates pristine spots in the recently accumulated mudflats. In the islands close to the ocean, the Baine (Avicennia marina) grows either in pure patches or in patches mixed with Keora. Along the streams, Rhizophora conjugata, Rhizophora mucronata, and Golpata are all often spotted plants.

Sparse Gewa and extensive Goran growth are the predominant plant types in the more salinized western region, with sporadic patches of Hantal (Phonix paludosa) growing on the dry land and riverbanks. Although decreased in size and diameter, Sundri and Passur are still present. Keora and the Golpata are also common along drainage streams and riverbanks.

The Sundarbans are home to 1586 animal species, of which 58 are mammals, 55 are reptiles, 339 are birds,120 are fishes, and 1104 are invertebrates,.

Sundarbans mangrove forest is the single largest home of the Royal Bengal Tiger (Panthera tigris)

This large carnivore is at the top of the ecological pyramid of the mangrove ecosystem, and the conservation of the Tiger will lead to the conservation of the unique biodiversity of the Sundarbans. Three large mammals; i.e. Spotted Deer, Wild Boar and Rhesus Macaque (Macaca mulatta); together comprise 95% of the biomass consumed by Tigers in the Sundarbans.

Sundarbans also harbors a good number of rare and globally threatened animals including Fishing Cat (Felis viverrina), Gangetic Dolphin (Platinista gangetica), Snubfin dolphin (Orcella brevirostris), Indo-Pacific Hump-backed Dolphin (Sotalia chinensis) River Terrapin (Batagur baska), Indian Civet (Viverricula indica), Rhesus Macaque (Macaca mulatta), Wild Boar (Sus scrofa), Finless porpoise (Neophocaena Phocaenoides), and Leopard Cats (Prionailurus bengalensis). The Sundarban supports healthy populations of two species of otters, viz. Oriental Small-clawed Otter (Amblonyx cinereus) and Smooth coated Otter (Lutrogale perspicillata).

Estuarine Crocodile (Crocodylus porosus), which has been identified as a critically endangered species in Bangladesh, is another flagship species in the Sundarbans.

A number of interesting amphibians occur in the Sundarban, viz. Green Frog (Euphlyctis hexadactylus) and Crab-eating Frog (Fejervarya cancrivora). Where apart from crocodiles, other reptiles like snakes are also found in large numbers. Out of 97 species typically 53 are present in West Bengal. Of the 17 species of snakes found in the Bangladesh Sundarban, 10 are sea snakes

A few of the other reptiles spotted in the region are Saltwater crocodiles, Water Turtles (Chelonioidea), Spotted Pond turtles (Geoclemys hamiltonii), Softshell turtles (Trionychidae), and Indian flapshell turtles (Lissemys punctata). The sea turtles consist of Olive ridley (Lepidochelys olivacea), Hawksbill turtle (Eretmochelys imbricata), and Green sea turtle (Chelonia mydas). River Terrapin (Batagur Baska) is another such endangered species that is epidemic in the region. Water monitor lizards are even spotted in large numbers.

The total bird species that number 339, including 130 winter visitor species, recorded in the Sundarbans is nearly half of the total bird species recorded in Bangladesh, while of the 12 species of kingfishers found in Bangladesh, 8 are found in the Sundarbans. It consists of Herons, Egrets, Cormorants, Storks, Green Pigeons, Sand Pipers, Large and Small Spoonbills, Darters, Seagulls, Teal, Partridges, great variety of Wild Geese and Ducks.

The creeks and rivers of Sundarbans are highly rich in Molluscs, Crabs, and Fish. The Sundarban supports 53 species of pelagic fish in 27 families and 12 demersal fish in 49 families.

The Ganges shark (Glyphis Gangeticus), White Spotted Shovelnose Guitarfish (Rhynchobatus djiddensis), Pondicherry shark (Carcharhinus hemiodon), and other endangered species of sharks and rays may be found here. The Indian Dog shark (Squalus acanthias), the Bull shark (Carcharhinus leucas), the Hammerhead shark (Sphyrnidae), the Blacktip shark (Carcharhinus limbatus), the Pale-edged stingray (Dasyatis zugei), and other animals can also be found in the region. A few of the other fish types include Topshe, Bhetki, Pomfret, Parshe, Gurjali, and Hilsa. 

Biodiversity of the Sundarbans is strongly influenced by the seasonal salinity content and sedimentation dynamics of its waterways, which in turn, are determined by seasonally and annually fluctuating freshwater flows and diurnal tides. Recent research demonstrates that plants' physiological activities were hampered due to their lowered respiratory rates caused by prolonged exposure to saline water inundation. Recent research relating fisheries habitat and river salinity has led to a considerable decline in the number of fish species in the region.

The top dying of Dieback leads to the death of the sundari trees (Heritiera fomes). This condition starts with a decline or death of foliage and twigs in the upper part of the tree, and gradually the symptoms extend downward. This gives a stag-headed condition to the affected trees.

Some of the most devastating tropical cyclones in the world have occurred in the Bay of Bengal. An analysis shows that out of 14 global tropical cyclones associated with the highest fatalities, nine have occurred in the Bay of Bengal.

On November 15, 2007, in the late hours, Cyclone Sidr made landfall in Bangladesh's south-western coast. According to the Indian Meteorological Department (IMD), the cyclone developed and reached peak speeds of 215 km/h (135 mph). Through wind damage, floods, and tidal surge, the storm damaged approximately 450,000 homes across 30 districts in Bangladesh. It was estimated that around a fourth of Bangladesh's Sundarbans Reserve Forest, had suffered damage.

The biggest natural catastrophes to hit the Sundarban since Cyclone Sidr was Storm Aila and storm surge. At least 339 people died as a result of the storm in Bangladesh and India, while more than 1 million more were left homeless. On May 25, Aila intensified into a strong cyclonic storm and made landfall. The Sunderban was submerged under 6.1 meters (20 feet) of water, and many tigers, along with deer and crocodiles, were said to have perished in Aila's storm surge.

Timeline of Cyclone happening in the Sundarbans