it is joined by the Jiri river from the north. From here the flow is westward into Cachar, then Karimganj District of Assam, then to Sylhet in Bangladesh having a co-distributary the Surma River, the other later becoming the Meghna before the Ganga-Brahmaputra delta. The Padma joins it to become the Meghna. Wildlife The Barak is among the richest rivers in the world as to aquatic biodiversity, as it contains more than 2,000 species of fish. Other creatures include River Barak or Siamese crocodile (a rare and endangered crocodilian), the susu dolphin, smooth-coated otter and black mugger crocodile. From its origin to its bifurcation at the border of Nagaland producing the Surma River the Barak is long. The biomes are extremely rich in wildlife and also very diverse in the entire stretch of the river including: Varzea forest (flooded rainforest) Los llamjao (flooded grassland and Savannah) Tidal forest (mangroves in vast Delta Avourei) Flora or vegetation of the Pats (flat-topped table mountains in India and western Cambodia) Very large tropical swamps. Environmental concerns Environmentalists have expressed concern over the way aquatic creatures and their habitats are being destroyed in the upper reaches of river in southern Assam. Prominent nature conservation NGO Society for Activists for Forest and Environment (SAFE) has pointed out that the tribals living on both banks of Barak have developed the harmful practice of blasting small gelatin sticks smuggled from Mizoram to kill fish. In the process, thousands of fish, young and mature, along with turtles, dolphins and other aquatic life organisms are killed. The Ganges river dolphin is endangered. The proposed Tipaimukh Dam on the river in northeast India – a political controversy between India and Bangladesh – could hasten its extinction, researchers warn. Making a plea for conservation, researchers from Assam state in a study that the dolphin, India's national aquatic animal is heading towards “local extinction” in the river system of the state. “Factors like poaching (for oil and meat) and accidental mortalities in fishing gear, gradual habitat degradation by sluice gates, embankments, disturbances like motorboats and aquatic pollution have resulted in the extirpation of the resident dolphin population from the Barak river system of Assam,” M.K. Mazumder, corresponding author of the study, wrote. See also List of rivers of India List of rivers of Bangladesh References External links Rivers of Assam Rivers of Manipur Rivers of Mizoram Rivers of India Rivers of Bangladesh