Roots versus Shoots in Nutrient Uptake by Aquatic Macrophytes in Flowing Waters

Abstract

Transplant experiments conducted in the South Saskatchewan River, Saskatchewan, Canada showed that the aquatic macrophyte, Potamogeton crispus, obtained most of its nutrients through the roots. When plants were grown in buckets containing high (602 μg∙g⁻¹ total phosphorus; 712 μg∙g⁻¹ total organic nitrogen) or low (258 μg∙g⁻¹ total phosphorus; 109 μg∙g⁻¹ total organic nitrogen) nutrient sediments and exposed to high (75 μg∙L⁻¹ soluble reactive phosphorus (SRP); 530 μg∙L⁻¹ total dissolved nitrogen (TDN), or low (10 μg∙L⁻¹ SRP; 323 μg∙L⁻¹ TDN) nutrient concentrations in the open water, biomass, shoot density and tissue nutrient concentrations were largely determined by sediment type, rather than open water chemistry. These results indicate that the roots are an important site of nutrient uptake for aquatic macrophytes in flowing waters.