This book provides an opportunity to understand the cause-effect relation between water resources development interventions and brackish water ecosystems in a developing country like Bangladesh. Because of the increasing water development interventions in Bangladesh, brackish water ecosystems have become a great concern at the present time. Being located in the south-eastern coastal area of Bangladesh, the Bakkhali River faces such type of threat. Due to the rubber dam construction across the river, the brackish water zone has been cut-off by establishing a distinct fresh and saline water zone affecting livelihoods of the brackish water dependent groups. The study reveals low availability of the indicator species in the zone. Finally, the study also argues that the impact on indicator species is due not only to the rubber dam construction across the river but also increased fisher folks and indiscriminate fishing practice considerably.