Comprehensive Assessment of Trophic Status and Chlorophyll-a Dynamics in the Jhelum River Basin: Implications for River Ecosystem Management

This study investigates the impact of environmental factors on benthic Chlorophyll-a (Chl-a) concentrations in river ecosystems, focusing on the Jhelum River Basin (JRB). It assesses the influence of hydro-chemical variables on Chl-a levels and trophic status across 59 sites spanning upstream, midstream, and downstream sections. The trophic status based on the mean and maximum concentration of Chl-a at various sites reveals the oligotrophic (76%) to mesotrophic (24%) nature of the JRB. Whereas, the concentration of total phosphorus (TP) revealed the mesotrophic (42%) to eutrophic (58%) nature of the JRB. Hierarchical cluster analysis (HCA) of data sets resulted in the formation of three distinct clusters. Cluster I was dominated by upstream sites (72%), cluster II was dominated by mid and downstream sites (71%), while cluster III was represented by main river and downstream sites (84%). Multiple linear regression (MLR) model (p<0.05) revealed TP (30-554 <mu>g/l) and dissolved oxygen (DO) (5-13 mg/l) as major parameters influencing Chl-a content. MLR also highlighted that ammoniacal nitrogen (NH3-N), nitrite nitrogen (NO2-N), electrical conductivity (EC), current velocity (V), discharge (D) and water temperature have significant relation (p<0.05) with Chl-a concentration but differ seasonally. Water quality index (WQI) on the basis of NH3-N, TP, DO, Chl-a and Faecal Coliform (FC) highlighted excellent to good for majority of upstream sites and poor to water unsuitable for all downstream sites respectively. The study offers clear signs of nutrient enrichment and increasing algal biomass downstream of JRB.