Impacts of pH and salinity on community composition, growth and cell morphology of three freshwater phytoplankton

Abstract

Impacts of climate change on phytoplankton species are very focusing issues nowadays. This research explored the probable impacts of different pH (pH 5.90 to 9.10) and salinity (0.60 to 3.0 ppt) concentrations on freshwater phytoplankton Chlorella vulgaris, Euglena granulata and Scenedesmus quadricauda. The initial community composition was 4:2:1 for the three taxa, which changed to 6:3:1, 6:2:1, 6:3.5:1 and 9:4:1 in pH 5.90, pH 9.10 and salinity 2.20 and 3.0 ppt respectively. E. granulata showed more tolerance in a wide range of pH (pH 5.90 to 8.30) based on growth rate studies. The other two species showed growth rates reduction gradually in changes with pH and salinity concentrations. Conspicuous changes of total biomass were seen in pH 5.90 and 9.10, and salinity 2.20 and 3.0 ppt conditions. Moreover, significant changes in cell morphology were found in pH 9.10 and 3.0 ppt salinity. The authors concluded that as group, the Chlorophytes were more susceptible than the diatom in these variable pH and salinity conditions, while S. quadricauda was comparatively more vulnerable as a single species.