Long-term variations in plankton community structure and environmental drivers in Korean artificial lake

With the intensification of global warming, the occurrence of harmful algal blooms (HABs) in freshwater ecosystems have become more prolonged and frequent. As phytoplankton and zooplankton are sensitive to changes in environmental conditions such as temperature, light intensity, and nutrients, understanding how environmental factors affect plankton community structure can help to predict the response of freshwater ecosystems to climate change. However, studies on the long-term monitoring of plankton community structure in Lake Soyang, an important source of drinking water for metropolitan areas in South Korea, and other domestic freshwater systems in Korea remain limited. Here, we investigated the changes in phytoplankton and zooplankton community composition in response to environmental factors in Lake Soyang during a long-term survey period. The results revealed that diatoms were negatively correlated (p < 0.001) with the water temperature and electric conductivity of the lake. Meanwhile, cyanobacteria and green algae, which appeared frequently in summer, were positively correlated (p < 0.05) with the pH and chlorophyll-a concentration of the lake. The occurrence patterns of diatoms were negatively correlated with all the zooplankton taxa identified in Lake Soyang; in contrast, the occurrence patterns of cyanobacteria, such HAB-causing <i>Microcystis aeruginosa</i>, and green algae were positively correlated with those of rotifera, copepoda, and protozoa. These findings will aid in predicting the impacts of climate change on freshwater ecosystems.