Decreasing flow of water through the rivers from upstream is destroying the ecosystem of Sundarban.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/rising-salinity-threatens-sundarban
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/new-age-bangladesh
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/bangladesh
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/forests
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sundarbans
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/salinity
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ecosystems
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/fauna
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ganga
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/brahmaputra
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india
[12] http://admin.indiaenvironmentportal.org.in/category/thesaurus/unesco
[13] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-resources
[14] http://admin.indiaenvironmentportal.org.in/category/thesaurus/world-bank
[15] http://admin.indiaenvironmentportal.org.in/category/thesaurus/biodiversity
[16] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environment