Photo : Collected
Sundarban biodiversity is facing destruction due to various harmful effects of climate change including salinity. Foresters say salinity has caused the worst damage to the flora and fauna of the Sundarbans in the past few decades. Sundari and less salt-tolerant trees are decreasing day by day in the forest. Again, many vines, which are food for most of the forest's animals, cannot grow in excess salinity. There has been a lot of research done at the individual and institutional level over the years on increasing salinity.
But there has not been much research on the challenges faced by forest tigers, deer, monkeys and other animals to survive in these changing conditions. As a result, there is no specific action plan for the protection of wildlife in any government-private organization. Even though the forest department has taken some steps to protect the animals, there are various questions in various quarters about whether it is sustainable. Long-term experience and looking at hazards in general. However, there is no research on how much these are useful for wildlife.
Stakeholders have called for specific research and action to address the extent of salinity increase and to protect the Sundarbans and its animals.
According to the information of the Forest Department, the area of the Bangladesh part of the Sundarbans is 6 thousand 517 square kilometres. This forest is spread like a net in Khulna, Bagerhat and Satkhira districts near the Bay of Bengal. 375 species of wildlife live in this largest forest in the country. These include 42 species of mammals, 35 species of reptiles and 8 species of amphibians. Apart from this, there are 300 species of birds.
According to the 2023 census, Sundarbans have 1 lakh 36 thousand 604 Chitra deer, 1 lakh 52 thousand 444 Monkeys, 47 thousand 515 wild Boars, 25 thousand 124 Guisap and 12 thousand 241 Hares. Apart from this, there are 150 to 210 Crocodiles in the 2017 survey and 113 Irrawaddy Dolphins and 118 Humpback whales in the 2019 survey. According to the latest survey in 2018, there were 114 Tigers in the Sundarbans. The Tiger count, which started again last year, will end next July. However, other animals have never been surveyed.
The Environmental Science Department of Khulna University conducted research on salinity in the Sundarbans River in 2020. It can be seen that the maximum amount of salinity in the dry season in the Pasura River of Sundarbans is 22.6 ppt (measurement of salinity – parts per thousand). But in 2010 it was 17.5 ppt. According to the researchers, the salinity of the river in the coastal area should normally be 2-5 ppt. There is no research on how much the tolerance of Sundarbans plants is higher than this.
Those concerned said that salinity also varies from place to place. Due to climate change increasing sea water pressure and decreasing freshwater flow from upstream, the salinity levels in Sundarbans water and soil have long exceeded levels. The amount of sedimentation is also increasing. In 2013, the amount of silt in the Harbaria area of Pasur River was 9 cm. In the 2019-20 fiscal year study, it was found to be 22 cm.
Professor of the Environmental Science Department of Khulna University and member of the National Committee of Bangladesh Poribesh Andolon Organization ( Eng Mean- Environmental Organization) has been researching the biodiversity of Sundarbans for a decade and a half. Abdullah Haroon Chowdhury. He said, that due to excess salt in the water, animal fur falls, skin diseases and wounds occur. Besides, essential food and water are not available.
Tanmoy Acharya, Wildlife and Biodiversity Conservation Officer of the Forest Department said, due to salinity, vines are not able to grow near the wetlands of the forest like before. They are food for many birds and animals. Apart from this, the number of tall trees including Sundari is decreasing. As a result, the breeding and reproduction of birds is decreasing.
Sundarban West Divisional Forest Officer Dr. Abu Nasser Mohsin Hossain said, that to take effective measures, a large-scale study is needed on the effect of increasing salinity on wildlife.
The Department of Wildlife Management and Nature Conservation deals with the animals of the Sundarbans. Nirmal Kumar Pal, divisional forest officer of this department, said that discussions are underway to bring under monitoring the extent to which dug ponds and high mounds constructed for shelter are useful for animals.
Khulna region forest conservator Mihir Kumar Dey said that under the Sundarban protection project, ecological monitoring will start in the forest for the first time next July. This research will be available on everything from salinity, pollution, effects of climate change, wildlife status to forests. Under this first, baseline data will be created. Thereafter survey will be done every 3 years. This work will be completed in 2025. Then any decision will be easy to make.
Meanwhile, environmental organisations say that the amount of salinity in the soil and the amount of the Sundarbans is increasing day by day and therefore, if effective measures are not taken scientifically, the biodiversity will disappear.
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