Sundarban and its majestic beast

Climate change has severely threatened biodiversity worldwide with many species already on the verge of extinction and is responsible for warmer temperatures, changing rainfall patterns, and more frequent extreme weather events. Climate change has already caused changes in vegetation, salinity and sedimentation in the Sundarbans — an iconic ecosystem and home to the Royal Bengal Tiger. Sea level rise (SLR) has further aggravated the loss of biodiversity and wildlife habitats particularly in coastal low-lying regions. The mean elevation of most of the Sundarbans is less than one meter (m) above sea level, making it also highly vulnerable to SLR. The combined effect of climate change and SLR is also the major cause of deforestation in the world. The Sundarbans, located in the north-eastern shores of India, is the world's largest contiguous mangrove forest spreading across approximately 9,630 square kilometres, of which, 5,363 square kilometres is reclaimed area and 4,267 square kilometres are protected mangrove forests. Another 6,000 square kilometres of contiguous mangrove forests are spread across neighbouring Bangladesh. Sundarbans is the most important biologically protective and taxonomically diverse ecosystem of the Indian Subcontinent. The entire area is a conglomeration of river channels, creeks and islands — about 102 islands are reported. Among them, 54 islands are inhabited and 48 islands are forested. The name "Sundarban" is, as reported, derived from the abundantly growing mangrove trees, locally called 'Sundari' (Heritiera fomes). The region is also home to a large number of threatened and endemic species, making it critical for integrated assessment and planning for effective conservation in the context of climate change and associated events.

Approximately 200 years ago, the Sundarbans measured about 16,700 square kilometres and was home to several species such as the Javan rhinoceros (Rhinoceros sondaicus), wild buffalo (Bubalusarnee), swamp deer (Rucervusduvaucelii), barking deer (Muntiacus muntjak) and leopards (Pantherapardusfusca) which, due to change in habitat and human-induced pressures, have now become locally extinct.

Tiger (Panthera tigris), the largest predator in Asia, historically distributed across much of the continent. The Bengal tiger (Panthera tigris) is one of the subspecies of tiger that is geographically restricted to Bangladesh, Bhutan, India, Nepal and Myanmar. The distinction between species and subspecies is sometimes hazy. Although two different subspecies can mate and produce viable offspring, subspecies often are separated by distinct habitats, different environmental adaptations and unique genetic and morphological features. Subspecies are evolution's intermediary steppingstones on the path to fully-formed species.

The Bengal tiger represents the largest remaining population (~67 per cent) of wild tigers in the world. An estimated 100,000 tigers roamed Asia's forests, swamps and grasslands a century ago. At present, 3,890 individuals are available globally after declining the number of wild tigers by 96 per cent due to habitat loss, hunting and illegal trade of tiger parts and these wild tigers are mostly confined to the protected areas. At present, approximately 1.5 million square kilometre tiger habitat representing only about 7 per cent is available with reference to a historical range. Among the eight subspecies of Panthera tigris, three (i.e., Panthera tigris balica; Panthera tigris virgata; Panther tigris sondaica) have already gone extinct and the rest are either endangered or critically endangered. According to the researchers, tiger habitats in the Sundarbans will vanish entirely by 2070. Sundarban is the world's only mangrove forest with tigers and the largest remaining Bengal tiger habitat in the world. Mangroves are recognised as environmentally critical ecosystems as they store a lot of carbon and are very important for trapping sediment along coastlines. Their role as nurseries for fish is often not appreciated. They are critical environments for crustaceans and fish, as well as acting as buffers for extreme weather events. Mangroves are an effective water regulation system, preventing shoreline erosion that also act as a shelterbelt against cyclones and tsunamis. The Sundarbans, due to its geographic location, is one of the world's largest and dynamic delta system and also at the forefront of climate change and related events.

Tigers mostly require a suitable prey base and good ground cover for hunting to persist, even in degraded forest. In this context, it is pertinent to mention that conservation areas are not strictly maintained by protecting sufficient habitat and prey, free from human threats, for self-sustaining tiger populations. Increase in global temperatures and polar ice-melting raise sea level that ultimately causes the influx of salinated seawater. Thereby, the growth of certain plants is inhibited and subsequently decreases the availability of certain food types. The Sundarbans' spotted-deer population, a key food source for the Bengal tiger, is likely to be affected as the tree leaves on which it feeds begin to disappear. All these factors are also responsible to destroy the Sundari trees and thus, tigers' mangrove habitat. As resources become scarce, tigers are more likely to stray into human settlements in search of food, increasing the chance of tiger-human conflict that manifested in the human killing, livestock depredation and, ultimately, the retribution killings of tigers by affected local communities. The loss of the world's largest mangrove ecosystem also raises concerns for human populations and other animal species. In addition to climatic factors, interaction with other species and environmental factors are also responsible to a greater extent for changes and losses of biodiversity at both the local and global levels. The future of many wildlife species will largely depend on their ability to adapt or tolerate a wide range of climatic conditions. Further, the Sundarbans are under growing pressure from industrial developments, infrastructure development, water divergence in upstream areas, wood collection, harvesting of other aquatic resources, agriculture, unsustainable collection of prey species, intensive fish farming, and poaching.

If we critically evaluate the impact of so-called human development, economic growth and progress of society, victims are the poor people and wild animals. Their natural surroundings are being jeopardised by agribusinesses and industrialists converting forests to fish farming, honey collection, infrastructure development, ship movement, resort and other industries. Naturally, a huge amount of public money is being spent for infrastructure in the name of development and progress of society as a 'proof' to establish the concern of the government, state apparatus, regulators and politicians. This development cuts across animal habitats and makes long-range movement more and more challenging as well as the suffering of humanity and damage to the ecosystem with valuable plants and animals. Many of us want to save wildlife but we have less and less space to do so because of the population explosion and rapidly increasing demands for more and more land.

Considering the above fact, it may be pointed out that tigers are getting a double whammy — greater human encroachment on the one hand and a worsening climate and associated sea-level rises on the other. At present, management of tigers is a response to global conservation crisis. Range contraction, population decline, habitat fragmentation, prey loss, and poaching cause and aggravate this crisis. If we are really concerned about tiger conservation, we must realise the importance of understanding the basic ecology of this apex predator, including the relationship between environmental and anthropogenic variables and habitat use. The government, both in Center and states, should prioritise tiger conservation by designating more areas for tiger conservation — creating corridors for transboundary tiger movements, incessant strict monitoring and law enforcement to control illegal human activity in the area — avoid unplanned development in the vicinity and raise public awareness to control human-tiger conflicts in the area. I believe that if conservation is prioritised, the population of Bengal tiger would continue to live in the Sunderban.

Dr Debapriya Mukherjee is a former Senior Scientist, Central Pollution Control Board. Views expressed are strictly personal