Benthic Macroinvertebrates as Bioindicators of Aquatic Health: A Review and Comparative Analysis of Diversity Indices for Water Quality Assessment

River ecosystems are critical to biodiversity and provide essential ecological services, with benthic macroinvertebrates serving as reliable bioindicators of water quality as they provide an integrated indication of past and present ecological conditions of aquatic bodies. The ubiquitous distribution, relatively long-life cycles, high accumulating capacity and sedentary nature of benthic macroinvertebrates, make them a great tool in assessing the health condition of aquatic ecosystems. The present study involves a comprehensive review and comparison of diversity indices commonly used in river monitoring. Data for the analysis were sourced from peer-reviewed articles, environmental reports, and case studies on river monitoring. This paper summarizes the role of benthic macroinvertebrates as bioindicators to evaluate the water quality of fresh water bodies using different bioassessment approaches which include Classical diversity indices such as the Shannon-Wiener, Simpson, and Margalef indices, Saprobic index, HBI index, BMWP score, NSF-WQI score, taxa richness and EPT ratio. The presence or absence of specific macroinvertebrate taxa reflects their differential tolerance to pollution. The classification of benthic macroinvertebrates with respect to tolerance values indicates the status of freshwater bodies. The paper aims to highlight applications and the methods used in biomonitoring, guiding river management, and supporting sustainable conservation strategies needed for the sustainability of aquatic resources.