Nutrient bioextraction and microalgae growth inhibition using submerged macrophyte Myriophyllum spicatum in a low salinity area of East China Sea

Highlights: • Myriophyllum spicatum was successfully cultivated in a low salinity sea area. • A new suspension-cultivation method for M. spicatum was constructed. • Nutrient bioextraction and phytoplankton inhibition by M. spicatum was remarkable. - Abstract: Myriophyllum spicatum was cultivated in a low salinity area of Hangzhou Bay (salinity 5.8–6.5), from August to October in 2016, to evaluate the abilities of its nutrient bioextraction and microalgae growth inhibition. During the 72-day cultivation period, M. spicatum had a specific growth rate (SGR) of 6.23% day^{− 1} and increased 20-fold in biomass (wet weight). Tissue C, N and P assimilation quantities of M. spicatum were found to be 3279.39 kg, 360.61 kg and 26.97 kg, respectively. The concentration of NH₄-N, NO₃-N, NO₂-N and PO₄-P after M. spicatum cultivation was decreased by 47.92%, 58.28%, 36.40% and 55.57%, respectively. The phytoplankton density was decreased from 1064.60 × 10⁴ cells L^{− 1} to 12.85 × 10⁴ cells L^{− 1}. These results indicated that cultivation of M. spicatum can help in nutrient bioextraction and microalgae growth inhibition in low salinity marine water bodies.