Effect of Potamogeton pusillus on Water Quality and Plankton CommunityEffect of Potamogeton pusillus on Water Quality and Plankton Community

In closed aquatic environments like ponds or lakes, water bloom caused by eutrophication has severely damaged aquatic ecosystems. Some previous studies suggested that submerged macrophytes contribute to the development of aquatic ecosystems and water purification. Although water purification and lake ecosystem restoration using submerged macrophytes have been greatly studied, their specific mechanisms remain unclear. We evaluated the effect of a submerged macrophyte Potamogeton pusillus on water quality and plankton community using mesocosms with and without the macrophytes. The concentrations of chlorophyll-a, total nitrogen and phosphorus, particulate nitrogen and phosphorus in the mesocosm with P. pusillus were lower than those without P. pusillus as long as the macrophytes thrived. The cell concentration of cyanobacteria was significantly decreased in the presence of P. pusillus, while differences for chlorophytes and diatoms remained minimal. The number of large-sized cladocerans (> 0.1 mm of body length), known as heavy grazers of phytoplankton, was markedly higher in the mesocosm with P. pusillus. Our results suggested that P. pusillus is potentially useful for water purification and aquatic ecosystem restoration.