I study the dynamics of phytoplankton and zooplankton in Lake Erie and the physical, chemical and biological drivers of those dynamics. Relying on the Lake Erie Plankton Abundance Study (LEPAS) plankton data set, NOAA climate data, USGIS river discharge data, and water chemistry data from Heidelberg University, I model long-term (1995-2020) changes in Lake Erie's phytoplankton and zooplankton communities. In particular, I focus on the causes (eutrophication, climate change) and consequences of harmful algal blooms (HABs) and of changes in plankton phenology during spring and summer.