Journal of Ecosystem & Ecography
Open Access

Abstract

Doon, a unique synclinal valley is surrounded by the lesser Himalaya and Shivalik mountain ranges in Uttarakhand. The Ganga river basin drains the eastern extremity and the Yamuna river basin drains the western extreme of the valley. All water sources (streams, pools and springs) were sampled at different 30 stations during 2006-2008, regularly at monthly intervals. Diatom samples were collected from 3x3 cm 2 area of the benthic substrate (cobble, vegetation) cleaned with acid and mounted in Naphrax. Overall, 358 diatom taxa are recorded for this valley comprising of various genus, species, subspecies and forms. 78 diatom taxa are observed as the dominant forms, based on the different habitats and ecological conditions prevailing in this valley. Diatom taxa such as Navicula minuscule var. muralis, Navicula constans var. symmetrica, Navicula radiosa, Cyclotella menenghiana, Gomphonema affine var. affine, Diatoma elongatum var. tenuis, Synedra inaequalis var. jumlensis and Amphora montana have come up as the dominant taxa found only at one station or grid. Navicula goeppertiana var. goeppertiana, Achnanthes gondwana, Achnanthes kryophila, Achnanthes exigua, Achnanthes heterovalvata, Cymatopleura amphicephala are among those dominant forms found only in one basin. Naviculla phyllepta is found abundant for main rivers and that too only during winters. Navicula cryptotenella as dominant taxa found throughout the valley but only in forest rich areas and with less disturbance. The study also gives a brief idea of the distribution of dominant forms of diatoms with the context of habitat and other ecological conditions of this large valley.

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