Spatial distribution and functional feeding groups of aquatic insects in a stream of Chakrashila Wildlife Sanctuary, Assam, India

Aquatic insects play important role in ecosystem functioning viz. nutrient cycling, primary production, decomposition and material translocation. The functional feeding group (FFG) approach is an attempt to classify organisms, especially insects, according to their role in the processing of organic matter. An investigation during 2011-2013 was carried out on aquatic insects in different stretches of a stream of Chakrashila Wildlife Sanctuary located in western Assam, North East India which is designated as Key Biodiversity Area (KBA) by IUCN. Physico-chemical properties of water of the stream like water temperature, dissolved oxygen, free-carbondioxide, pH, total alkalinity, electrical conductivity, phosphate and nitrate were estimated to correlate the aquatic insects of specific functional feeding groups with water quality. A total of seventeen species was recorded during the study period. Record of nine species in first year and fourteen species in second year under different functional feeding groups (FFG) showed altitudinal variation. Highest percentage of predators was found in upstream. Collectors were recorded in upstream and downstream and shredders were recorded in midstream.