Composition and dynamics of epilithic algae in a forest stream at Shillong (India) |
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Authors: | Jayashree Rout J. P. gaur |
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Affiliation: | (1) Department of Biochemistry, School of life Sciences, North-Eastern Hill University, 793 014 Shillong, India;(2) Centre of Advanced Study in Botany, Banaras Hindu University, 221 005 Varanasi, India |
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Abstract: | The seasonal dynamics of epilithic algae in a third order pristine forest stream were analyzed over a period of 2 years. Stream water was slightly acidic and nutrient poor. Encrusting, filamentous flocs, and filaments were found. Algal standing crop was high (mean concentration of Chl a 16–43 mg m–2) in spring. Filamentous algae contributed most to standing crop. Diatoms made up over 85% by number of the epilithon. Blue-greens were abundant upstream, and chlorophytes downstream. This shift was ascribed to greater light availability downstream. The community was more diverse during spring. Water current was the most important variable regulating epilithon structure. Total phosphorus (TP), orthophosphate (O-POinf4su3–), silica (Si4+), nitrate (NOinf3su–) and conductance correlated negatively with flow rate. Green algae showed a positive correlation to phosphorus during low and stable flow. During rapid runoff, diatoms were the most resistant forms. Seasonal change in the epilithic community was mainly regulated by fluctuations in flow rate. |
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Keywords: | Canonical Correspondence Analysis diatoms epilithic algae forest stream seasonal variation |
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