Allelopathic effects of Egeria densa on the growth and morphology of Chlorella vulgaris

Interspecific interaction between submerged macrophytes and phytoplankton is of great significance in sustaining ecological balance and restoring eutrophic water regions. In consideration of the diversified algal density and macrophytes biomass, the present study selected two biomass levels of Egeria densa and gradient densities of Chlorella vulgaris for simulated cultivation experimentation. E. densa could significantly suppress the growth and affect the morphology of C. vulgaris. The allelopathically inhibitory growth of C. vulgaris was suggested to increase with increasing biomass of E. densa and decreased with the elevating density of C. vulgaris. Higher amount of colonies and bigger colony size of C. vulgaris were detected after the treatment with 5 g/L of E. densa together with C. vulgaris (OD680 = 0.2) and treatment with 10 g/L E. densa together with C. vulgaris (OD680 = 0.05). Elevated extracellular and intracellular polysaccharides were detected, which possibly contributed to the morphological changes of C. vulgaris induced by E. densa.