To explore the effects of different water levels on competition of submerged plants, we selected the canopy submerged plant Potamogeton malaianus Miq. and the erect submerged plant Hydrilla verticillata (L. f.) Royle as study materials. Four water level gradients (25, 50, 75, 100 cm) were chosen to simulate the hydrological environment of shallow depressions in the main distribution area of submerged plants in the field. The competition between P. malaianus and H. verticillata under different water levels was investigated by measuring plant height, root length, stem thickness, number of leaves...