Response of aquatic organisms as an eco-biotic indicator with response to cyclonic intervention in the large river system: A case study of river Ganga, India, during cyclone YAAS

Cyclonic interferences can adversely affect the riverine ecology and ecological niche of many aquatic organisms. The present study evaluates the impact of the cyclonic storm “Yaas” on the different abiotic as well as biotic variables (Plankton, Fish, and Benthos) of the river Ganga. In the study, it was observed that cyclones have affected the riverine water quality, as prior to Yaas the calculated “National Sanitation Foundation” - Water Quality Index was 70.52 and during the Yaas period, it reduced to 52.8, while, the observed value during the post-Yaas period was 68.2. The phytoplankton density varied from pre-Yaas period (6284 cell −1 ) to Yass (670 cell −1 ) and finally during post-Yaas period (196 cell −1 ). Contrary to phytoplankton, zooplankton responded favorably as its density increased from pre-Yaas period (196 cell −1 ) to Yaas period (370 cell −1 ), and during the post-Yaas (24 cell −1 ). The Fish and Benthic organisms also showed similar responses as to zooplankton.