Study on the Macroinvertebrates Community, A Bio-Indicator of Water Quality in Deepor Beel (Ramsar Site), Assam

Abstract

Given the limited and geographically narrow research on macroinvertebrate distribution in subtropical wetlands, this study aims to provide a comprehensive assessment of species assemblages and ecological health across multiple sites in Deepor Beel, a well-known wetland and Ramsar Site in north-eastern India. The current study examines the complex impact of anthropogenic pressures on benthic macroinvertebrates. During the post-monsoon and winter seasons of 2023–2024, samples were collected systematically from three important locations, including touristic destinations (Station-1), garbage dump sites and densely inhabited areas (Station-2), and flow-out points (Station-3). The recorded dataset includes 467 members from 14 families spread throughout 8 orders and 3 separated phyla. The phylum Mollusca appeared as the major taxonomic group (53.74%), controlling the gathered samples, with Arthropoda (45.18%) and Annelida following in hierarchy. Within this taxonomic framework, significant information was discovered, identifying Viviparidae, Lymnaeidae, and Planorbidae as the most abundant families, accounting for 16.27%, 15.84%, and 15.84% of total individuals, respectively. Furthermore, an in-depth examination of richness (Margalef richness) and diversity (Shannon-Wiener Index) indices demonstrated a deteriorating tendency from areas less affected by human interventions to those bordered by a trash dump and residential agglomeration. Macroinvertebrate saprobic scores show that Station-3 near the flow-out point to the river Brahmaputra (5.5) is in good environmental condition, whereas Stations-1 and 2 (4.9 and 4.66) are moderately polluted and impacted by anthropogenic activity. Redundancy analysis highlights the association between moderate pollution indicator taxa Gerridae (Hemiptera), Hydrophilidae (Coleoptera), and Hirudidae (Hirudinea) and increasing organic loads (BOD, COD) at Station-1 and 2. The combination of macroinvertebrate family data and water quality parameters underlines the need for a comprehensive approach to assess the health and sustainability of lake ecosystems. The study's findings have implications for developing educated conservation and management policies in the face of growing anthropogenic threats.