Ecology of Binwa stream district Kangra H P with special reference to morphological adaptations of aquatic insects

Abstract

Present investigation embodies an account of ecological studies of Binwa, a Western Mid Himalayan hill stream of district Kangra, Himachal Pradesh. For the study four observation sites have been selected on different altitude i.e., Kharli (S1), Baijnath (S2), near Chobin (S3) and Triveni (S4) and water samples were collected on monthly basis for two year (March 2011-February 2013). Geo-morphological studies of the stream revealed that it is B-3 type, while longitudinal profile reported fall in gradient from head to mouth and its water current become gentler downstream section. The major aspects of the studies include hydrobiology and morphological adaptations of the aquatic insect fauna of the stream. Hydrobiological studies include physico-chemical analysis of the water samples helped to determine the water quality, while population dynamics of planktons determined the trophic status of stream. Phytoplankton (36 species) constituted the major component and zooplankton (17 species) as minor component, while Bacillariophyceae among phytoplankton, and Rotifera among zooplankton showed dominance both in terms of abundance and diversity. Planktons showed abundance during winter and post monsoon months. Diversity indices showed changed trophic status from oligotrophic to slightly eutrophic downstream. PCA studies helped in identifying the major variables involved in determining and influencing the biota of stream. WQI and EPT index reported downfall in water quality downstream due to anthropogenic interferences. Several body shapes (stream line, dorsoventrally flat), clinging (tarsal claws of various shapes), fixing, suction (suckers), friction generating (friction pads and adhesive apparatus), particular behavioral responses (unique sitting posture, drifting, scorpion posture and photo tactic responses) and specific mouth parts, are the different devices observed in the studied aquatic insects belonging to six orders.