TANVEERA TABASUM
Abstract
Benthic macroinvertebrates are important components of freshwater ecosystems and provide valuable information on ecological responses to environmental disturbance. The present study examined the functional and ecological organization of benthic macroinvertebrate assemblages across the regulated Delhi stretch of the Yamuna River and its associated floodplain wetlands. Seasonal observations from river sites (R1âR7) and floodplain ponds/lakes were evaluated in relation to spatial variation in environmental conditions, with emphasis on taxonomic composition, functional feeding characteristics, pollution tolerance, and habitat association. A total of 55 benthic macroinvertebrate taxa representing Mollusca, Insecta and Annelida were recorded. Assemblage structure varied markedly among sites, with relatively diverse communities occurring at less disturbed river reaches and at sites associated with comparatively favourable habitat conditions, whereas heavily impacted reaches were characterized by reduced representation of sensitive taxa and greater occurrence of pollution-tolerant forms, particularly oligochaetes and chironomids. The distribution of functional groups indicated a shift from comparatively diverse feeding and trophic strategies in less disturbed habitats towards greater representation of deposit feeding and tolerant taxa under degraded environmental conditions. Floodplain ponds and lakes supported additional taxonomic and ecological components, highlighting their potential contribution to habitat heterogeneity and biodiversity conservation within the regulated riverâ floodplain landscape. The findings demonstrate that consideration of functional organization alongside taxonomic composition can provide a broader understanding of benthic responses to pollution and habitat alteration. Integrating functional indicators with conventional biological and physicochemical assessments may therefore improve ecological evaluation and support pollution management, habitat conservation, and restoration planning for the Yamuna Riverâfloodplain system.