Nutrient combined hydrodynamic mixing facilitates Microcystis dominating phytoplankton communities: evidence from a microcosm experiment

Nutrients and hydrodynamic mixing are both important environmental factors affecting the growth of Microcystis. Effects of nutrient combined with hydrodynamic mixing in the dominance of Microcystis in phytoplankton community is unclear. Here we present data on the effects of hydrodynamic mixing (HM), nutrient addition (+ N + P), and hydrodynamic mixing combined nutrient addition (HM + N + P) on dominance of Microcystis in a microcosm experiments. Results showed that the average number of Microcystis in HM + N + P was 10.09, 3.79, and 1.95 times that of the control (9.19 x 10(6) cells L-1), + N + P, and HM group, respectively. Moreover, the mean colony sizes of Microcystis in HM + N + P group were 2.08, 1.91, and 1.21 times that of the control (24.42 mu m), + N + P,HM group, respectively. Pseudanabaena limnetica replaced Microcystis as the dominant species in control, + N + P, and HM group at end of the experiment, with 82.21%, 90.65%, and 50.37% of total algae number, respectively. However, in HM + N + P group, Microcystis dominated throughout the experimental period, accounting for 73.56-94.67% of the total algae abundance. Results demonstrated that N and P combined with hydrodynamic mixing promoted abundance, colony size of Microcystis, which plays an important role in the dominance of Microcystis in phytoplankton community in natural ecosystems.

Automated summary

This study reveals the importance and interaction between hydrodynamic mixing and nutrients in the growth of Microcystis. The results show that the combined effect of hydrodynamic mixing and nutrient addition can promote the abundance and colony size of Microcystis, playing an important role in its dominance in phytoplankton community.