Difference In Water Levels Affects Migration Of Fish To Inland Water Bodies Malappuram: A detailed study conducted in rivers in the state reveals that the alteration in natural flow of rivers is obstructing the connectivity in river-related ecosystems, besides affecting the breeding and feeding movement of fishes. The study — conducted in 44 rivers from Manjeswaram river in Kasaragod to Neyyar river in Thiruvananthapuram —as part of the river fish monitoring programme of the state biodiversity board (KSBB) says the loss in connectivity also impact the fish diversity in rivers. It was conducted by various local NGOs for the KSBB and compiled by the River Research Centre, Thrissur. The study report has been submitted to the KSBB with various recommendations for the better future of rivers in the state. It says the alteration in natural flow of rivers is happening due to sand mining, reclamation of floodplains and wetlands, river banks and riparian habitats. It points out the difference in water levels in rivers and their related ecosystems such as tributaries, streams, canals and ponds is the main obstacle for the smooth migration of fish from rivers to inland water bodies. The report has sought immediate measures from the government for restoring connectivity between rivers and their associated ecosystems. Board member secretary Lala Das said the loss in connectivity has reduced the number of species of fishes in state rivers, which were known for their diversity. Dr Latha of River Research Centre said the study was an attempt to monitor the riverine ecosystem of Kerala as well as the fish habitat for ascertaining its condition.