Fish diversity, assemblage pattern along with the environmental variables in tidal fresh water stretch in the Hooghly estuary of Gangetic delta, West Bengal, India

Abstract

Abstract The greatest estuary created by the Gangetic delta in India is the Hooghly estuary. Despite their importance to the estuarine biodiversity, the tidal freshwater areas of this estuary have gained little interest from ecologists. Present study aims to explore the fish diversity with its assemblage pattern and their relationship with physico-chemical parameters from June 2020 to May 2021. There have been identified 118 species in total, from 14 orders and 47 families, with seven (7) being near threatened, fifteen (15) vulnerable, four (4) endangered, and eight (8) not evaluated. Perciformes (29.66%), Cypriniformes (22.88%), and Siluriformes (21.18%) accounted for 73.72% of the overall species count. Station-1 has significantly higher species richness, rarefied richness, and abundance. Station-3 and station-2 followed station-1 respectively. The composition of fish species changed significantly among the stations, as shown by cluster analysis, nMDS (nonmetric multidimensional scaling), ANOSIM (analysis of similarities), and SIMPER (similarity percentage analysis) (p < 0.05). The canonical correspondence analysis revealed that alkalinity, conductivity, phosphate, and total carbon dioxide of the water were the key environmental parameters. In addition to defining a sustainable management method for the fish resources in the Hooghly estuary, this effort will act as a baseline study for further investigation.