Bangladesh | The Daily Star | January 25, 2017 | Staff Correspondent:
Increasing salinity in the water and soil of the Sundarbans due to climate change will leave a significant impact on the tree and fish in the mangrove forest in near future, predicts a World Bank study.
Some iconic tree species like Sundari, Passur and Kankra and a few freshwater fish species are likely to be extremely rare in the Sundarbans.
Climate change coupled with human activity-induced consequences will have significant implications for the present and future management of the Sundarbans as well as the forest-dependent livelihoods of the surrounding poor inhabitants, the study added.
The report was released yesterday on the World Bank’s website. It comes at a time when environmentalists from home and abroad have been protesting a government move to establish a coal-fired power plant near the Sundarbans, a Unesco natural heritage site, jointly by two state-owned companies from Bangladesh and India.
According to the WB, the Southwest coastal region of Bangladesh is already facing increasing salinity, especially between October and May. Laboratory analyses of water and soil samples show an increase in salinity over time in the region.
This trend of increasing salinity will be aggravated in the coming days due to effect of climate change. It will alter the ecosystem of the forest and leave a deep impact on its flora and fauna. The spawning pattern of some of the aquatic species will change, the study said.
Soil salinisation is likely to lead to a significant decline in the output of high-yielding variety of rice which ultimately impacts on the poor farmers’ livelihood.
The increasing water salinisation will change the availability of many freshwater fish species. Some of them will migrate from the Sundarbans area as the salinity is likely to adversely affect their reproductive cycle and capacity, extent of suitable spawning area and their feeding and breeding.
“This will lead to a striking loss of habitat of freshwater fish in the western part of the Sundarbans,” the study stated.
Though some of the brackish fish species will increase, that would be insignificant in comparison to the reduced fresh water fish species. It will leave a deep impact on the poor community as their income would reduce and they would be deprived of their main protein source.
The analysis looked into the salinity tolerance range of 83 fish species typically found in the region with expected location-specific water salinity resulting from climate change by 2050.
Regarding the vegetation pattern, the WB study predicts significant losses for Sundari and Passur-Kankra, along with gains for Gewa, Baen and Goran. The stock of Sundari, the highest value timber of the Sundarbans, has been declining over time due to natural causes such as “top-dying-disease” which has killed millions of trees since 1970. Climate change is likely to worsen this depletion of Sundari stock through increased salinity.
The analysis compared the different salinity tolerance ranges for 14 varying dominant mangrove species detected in 2013 satellite images of the Sundarbans with the expected salinity for alternative scenarios of climate change by 2050.
“Since changes in the Sundarbans’ ecosystem induced by rising salinity are likely to change the prospects for forest and fishery-based livelihoods, resources should be directed to the development of alternative livelihoods for ecosystem-dependent household,” the report said quoting Susmita Dasgupta, lead environment economist of the Development Research Group, as saying.