AQUATIC ECOLOGY, vol.56, no.1, pp.89-98, 2022 (SCI-Expanded)
Loss of submerged macrophytes resulting from high turbidity has become a global environmental problem in shallow lakes, associated with eutrophication. To help macrophyte recovery, application of artificial light-emitting diodes (LEDs) has been proposed to complement nutrient load reductions. We set up a mesocosm experiment to test if LEDs could compensate for shading effects from phytoplankton. We incubated three submerged macrophytes (Vallisneria natans, Myriophyllum spicatum and Ceratophyllum demersum) in 12 tanks of 1000 L under three artificial LED light treatments (red, blue and white) for 94 days in summer. The results showed that 1) growth of V. natans and M. spicatum was stimulated in all the LED light treatments, while C. demersum died in the end of the experiment in all treatments. The growth variables (MLShoot, DMShoot) of V. natans in blue, red and white treatments were 1.8-4.5 times greater than those in the control treatment. For M. spicatum, all plants only survived in the treatments with artificial light supplement. 2) Growing status of V. natans was similar among the treatments of different light colors, while M. spicatum grew best in the red light treatment. The results suggest that artificial light, particularly red light, can promote the recovery of submerged macrophytes in waters where impaired light climate would prevent or delay growth of macrophytes and recovery from eutrophication. Further large-scale field studies are, however, needed to fully elucidate the potential of using artificial light to stimulate growth and recovery of submerged macrophytes in shallow lakes.