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Carbon, Nitrogen, and Phosphorus Stoichiometry and Eutrophication in River Thames Tributaries, UK
- D. R. Smith, H. P. Jarvie, M. J. Bowes
- Agricultural & environmental letters 2017 v.2 no.1 pp. -
- biomass, carbon, chlorophyll, eutrophication, nitrogen, phosphorus, phytoplankton, primary productivity, river water, rivers, stoichiometry, England
- Primary productivity in aquatic systems relies on carbon (C), nitrogen (N), and phosphorus (P) availability, with a reference stoichiometric ratio of 106 C/16 N/1 P, known as the Redfield ratio. This paper presents a methodology to visualize river water C/N/P stoichiometry and examine phytoplankton response. Redfield total dissolved C/N/P concentration ratios (TDC/TDNR/TDPR) from five River Thames tributaries were plotted in a ternary diagram, allowing relationships between nutrient stoichiometry, total P concentrations, and chlorophyll a, as a surrogate for phytoplankton biomass, to be explored. Chlorophyll a concentrations above 100 μg L⁻¹ were not observed below 14% TDPR, and concentrations above 30 μg L⁻¹ were not observed below 13% TDPR. This indicates a potentially lower TDPR limit for highly eutrophic waters. These rivers are C and N rich, and this methodology should be applied to a wider range of rivers to explore C, N and P thresholds across different river typologies.