Author(s): Usha Pandey; Jitendra Pandey; Ekabal Siddiqui

Linked Author(s):

Keywords: Diatom; Elemental stoichiometry; Ganga River; Nutrient limitation

Abstract: The present study was conducted from March 2016 to February 2017 to investigate human-driven shifts in N:P:Si stoichiometry along a 2320 km stretch of the Ganga River. Concentrations of nutrients ( NO 3 − , NH 4 + and PO 4 3 − ), dissolved organic carbon (DOC) and dissolved silica (DSi) were measured in river water and in surface runoff to explore possible role of lateral flow and evaluate if there was a shift in the elemental stoichiometry of N, P and Si. Our study revealed that catchment runoff is an important factor, in addition to urban-industrial flushing, enhancing nutrient enrichment causing a shift in N:P:Si ratios leading to N limitation over P (N:P 1). Among the seven dominant diatom genera considered here, diatom abundance changed with concurrent changes in water chemistry. Sites with overall low N:P ratios favoured P-loving species such as Diatoma vulgaris , Fragilaria intermedia and Gomphonema parvulum . The study shows that the N:P:Si stoichiometry if coupled with changes in diatom abundance may be a useful predictor of anthropogenic environmental effects in the Ganga River. This watershed scale study invite attention towards significance of N:P:Si stoichiometry for properly addressing the eutrophy and efforts to rejuvenate the river.

DOI: https://doi.org/10.1080/15715124.2018.1476370

Year: 2019