Ann. Limnol. - Int. J. Lim.
Volume 54, 2018
|Number of page(s)||13|
|Published online||21 November 2018|
Seasonal variations in response of periphytic algal community to nutrient enrichment in the river Ganga (Varanasi, India)
Laboratory of Algal Biology, Department of Botany, Institute of Science, Banaras Hindu University,
2 Department of Botany, School of Life Sciences, H.N.B. Garhwal University, Srinagar, Garhwal 246174, India
3 Department of Chemical Engineering and Technology, Indian Institute of Technology (BHU), Varanasi 221005, India
4 Department of Plant Science, Faculty of Applied Sciences, MJP Rohilkhand University, Bareilly 243006, India
* Corresponding author: firstname.lastname@example.org
Accepted: 18 September 2018
Effect of nutrient enrichment on periphyton was studied using chemical diffusing substrates that released, singly or in combination, PO43−-P and nitrogen, both NO3−-N and NH4+-N. The study was carried out in March and June 2014 as these two time periods showed abundance of different groups of algae. Whereas diatoms and green algae were abundant in March, cyanobacteria dominated in June. Nitrogen was primarily growth limiting in river water as its enrichment enhanced the growth of periphyton. Phosphate limitation was secondary in nature. Enrichment of NH4+-N caused greater enhancement of periphytic growth than that of NO3−-N. Nutrient enrichment reduced species diversity, further enhancing total biovolume of the periphytic group that was predominant at that particular point of time. Nutrient enrichment markedly increased cyanobacterial populations in June due inter alia to high temperature. In spite of nutrient enrichment, the periphytic biomass did not reach the level (chl a ≥ 100–150 mg m−2) considered as the nuisance, except in March when combined enrichment of PO43−-P and NO3−-N greatly enhanced the periphytic biomass.
Key words: periphyton / chemical diffusing substrate / nutrient limitation / nitrogen / phosphorus
© EDP Sciences, 2018
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