India’s river interlinks may carry invasive species to more basins, study warns

Bengaluru: India’s ambitious National River-Linking Project, which proposes to link 37 major river basins through 30 links, could accelerate the spread of invasive alien species and aquatic pathogens across the country, new research has found.

The project, considered the world’s most ambitious of its kind, aims to redistribute around 174 billion cubic metres of water from ‘surplus’ to ‘deficit’ basins while generating some 34,000 MW of power.

But experts have long warned about its environmental costs, saying the idea of ‘surplus’ and ‘deficit’ basins masks seasonal variations in river flows, and that transferring water can alter downstream flows, sediment transport, floodplains and deltas.

The latest concern is biological invasion.According to research, the Lower Ganga basin hosts 13-15 invasive alien species and could become a major source of invasives for the Mahanadi basin, which is home to 69 threatened species. Water connections created under the interlinking project could also help aquatic pathogens spread and flatten the unique biota that individual river basins boast today.

The study also found that peninsular basins are more vulnerable to biological invasions than those in Central and North India.

Dams, reservoirs and canals built for interlinking can break ecosystems into pieces, disturb fish migration and other ecological processes, and create new corridors for species to move where they would never naturally reach.

Researchers say each river basin in India currently hosts a unique assemblage of fish and other aquatic life evolved over millions of years. Linking them could homogenize this diversity, with invasive species outcompeting native ones.