The uptake kinetics of phosphate (Pi) by Myriophyllum spicatum was determined from adsorption and absorption under light and dark conditions. Pi uptake was light dependent and showed saturation following the Michaelis-Menten relation (in light: V = 16.91 x [Pi](1.335 + [Pi]), R-2 = 0.90, p < 0.001; in the dark: V = 5.13 x [Pi](0.351 + [Pi]). R-2 = 0.77, p < 0.001). Around 77% of the loss of Pi in the water column was absorbed into the tissue of M. spicatum, and only 23% was adsorbed on the surface of the plant shoots. Our study shows that M. spicatum shoots have a much higher affinity (in light: 3.9 mu mol g(-1) dw h(-1) mu M-1; in the dark: 3.7 mu mol g(-1) dw h(-1) mu M-1) and V-max (maximum uptake rate, shoot light) for Pi uptake than many other aquatic macrophytes (in light: 0.002-0.23 mu mol g(-1) dw h(-1) mu M-1; in the dark: 0.002-0.19 mu mol g(-1) dw h(-1) mu M-1), which may provide a competitive advantage over other macrophytes across a wide range of Pi concentrations. (C) 2011 Elsevier B.V. All rights reserved.