Winter severity shapes spring plankton succession in a small, eutrophic lake

Springtime in temperate lakes is characterized by a phytoplankton bloom, followed by a grazing crustacean zooplankton bloom. Timing and species composition for both phytoplankton and zooplankton peaks are likely dependent on antecedent conditions and may respond to climate change. Here, we tracked winter-spring plankton phenology for four years in a shallow, eutrophic lake. Winter conditions influenced successional events and species composition for both phytoplankton and zooplankton. Specifically, diatoms dominated around ice-out followed by cyanobacteria blooms in the late spring. Cyclopoid copepods were common under ice, whereas Daphnia increased with higher water temperature later in the season. Phytoplankton and zooplankton species composition responded to water temperature, ice-off, and exhibited inter-annual variation, while phytoplankton also responded to nutrient concentrations and biomass of some zooplankton groups. Zooplankton species composition also corresponded with secchi depth. Interestingly, the ice broke up and re-froze during the warmest winter studied, which allowed water column mixing and caused colder water temperatures than water temperatures under ice. In this particular study year, the spring Daphnia bloom was late relative to other years, indicating a possible mismatch between the phytoplankton and zooplankton blooms. Our study indicates that winter conditions have a strong impact on plankton phenology and community composition.

Automated summary

Springtime in temperate lakes is characterized by a phytoplankton bloom, followed by a grazing crustacean zooplankton bloom. The timing and species composition of these events may be influenced by antecedent conditions and climate change. Winter conditions have a strong impact on the succession and species composition of both phytoplankton and zooplankton.