Ecological studies on the macroinvertebrates of a hill stream impacted by anthropogenic activities in Western Himalaya

Abstract

newline xiv newlineAbstract newlineThe Indian state of Himachal Pradesh, a constituent of the Himalayan Biodiversity Hotspot, is bestowed with an intricate network of freshwater perennial torrential streams, which constitute an important source of fisheries as well as source of water for irrigation and drinking purposes. Various anthropogenic activities have immensely impacted streams endangering aquatic biodiversity especially at lower and middle elevations. Benthic macroinvertebrates are sensitive to changes in different physico-chemical and biological metrics, which make them ideal bio-monitoring tools for assessing anthropogenic impacts. The aim of present studies was to investigate how macroinvertebrate assemblages of a stream changed both structurally and functionally in relation to temporal and spatial scales as the stream coursed through a pristine-urban-rural land use gradient. newlineThe stream was sampled at monthly intervals during a period of two years (2014-16) for benthic macroinvertebrate community, environmental variables and food resources. Species richness index was lower at urban and rural sites as compared to less impacted pristine site. Among functional feeding groups, collector-gatherers, scrapers and predators were most abundant at pristine site and decreased along the land use gradient. Collector-filterers were most abundant at rural site. Shredders were absent at rural site and least represented at pristine and urban sites. In terms of potential food resource, average amount of fine particulate organic matter was maximum at rural site. The single stream biotic disturbance appeared to be change in macrobiotic assemblage favouring collectors against scraping organisms. newlineThe density of macroinvertebrates decreased along pristine-rural gradient of the stream. The urban site at Bajhol was determined to be most polluted as indicated by high Hilsenhoff biotic index and BOD values. One way ANOVA was performed to determine tests of significance between various metrics. newlineKeywords: Anthropogenic activities, Benthic, Macroinvertebrates, Hill stream, Himalaya