ECOLOGICAL IMPACTS OF FLOATING MACROPHYTES MATS IN DAM RESERVOIR

Abstract

 Water lettuce, Pistia stratiotes L. is widespread in tropical and sub-tropical regions. The excessive growth of water lettuce causes ecological and socio-economic problems, however, there is few filed data on water quality under the dense mats formed by the invasive floating macrophyte in Japan. We conducted the field observation in the Turuda-Dam reservoir whose water surface were covered by water lettuce mainly. The results showed that the mats lowerd light intensity, phytoplankton productivity and dissolved oxygen concentrations near the water surface. In addition, it was confirmed that the water temperature was adequate for overwintering of water lettuce in the winter of 2020.