Benthic algae used in the uptake experiment was grown on sixteen rounded plastic gauzes in a glass tank (50 cm × 30 cm × 40 cm) containing 50 L of lake water. The diameter of each plastic gauze was 65 mm and the mesh size was 2 × 2 mm; the plastic gauzes were suspended below the water surface in the glass tank and formed a substrate for algae growth. To promote algae growth, the calculated doses of 1.5 mg N, as sodium nitrate, and 0.1 mg P, as sodium dihydrogen phosphate, were added into the glass tank per liter water per week (Wolfe and Lind, 2010). The water in the glass tank was kept at 30°C and in a light–dark cycle of 12 L:12 D, with an average light intensity about 100 μmol/(m2·s) in daytime and darkness at night. After four weeks, there were abundant benthic algae on the plastic gauzes. At the end of the four-week culture period, the benthic algae were transferred to another glass tank with 50 L of lake water and cultured for another 24 h in order to adapt to the experimental water conditions. Prior to the initiation of the experiment, the algae-encrusted plastic gauzes were washed gently with lake water to remove any nutrients adhering to the surface of the algae.