Sediment Chemistry and Substratum Characteristics as Determinants of Benthic Community Structure in River Jhelum: A Secondary Data-Based Review and Analytical Assessment

Abstract

River sediment is a geochemical storage site, physical habitat, and exposure pathway for benthic organisms. This article studies how sediment chemistry and substratum variability may contribute to the presence and abundance of benthic macroinvertebrates in the River Jhelum and its Kashmir Himalayan tributaries. It differentiates direct evidence of the Jhelum from other studies concerning dominating processes. A priority was given to studies published during the years 2020 to 2025. Data across the Jhelum Basin show that benthic communities vary along the longitudinal axis of the river and within different seasons. The finer sediments that compose a habitat type, together with pH, temperature, discharge, habitat type, and the degree of disruption of natural flow regimes, are important factors influencing the structure of the benthic community. Studies of the upper reaches of the river basin show that the agricultural, built-up, and mineral disturbance of the catchment influences the chemical and physical nature of the sediment available to form benthic communities. Several field and experimental studies show that excess fine sediment may reduce interstitial space, inhibit hyporheic exchange, and hyporheic refugia, thereby adversely affecting sensitive rheophilic taxa. The addition of organic matter may change food resources and the oxygen demand of the sediments. Bioavailable fractions of metals present in sediments should also be addressed. The suggested evaluations support direct Jhelum evidence of substratum and flow pathways, broad hydrochemical controls, and insufficient direct sediment-metal-to-benthos evidence. A suggested standardized monitoring program includes grain-size fractions, sediment organic matter, embeddedness, nutrient chemistry, metal fractionation, hydrology, and macroinvertebrates and DNA-based taxonomy.