United States - April 23, 2025 Lake Okeechobee, Florida – Researchers have mapped the daily movement of harmful algal blooms in Lake Okeechobee, Florida’s largest freshwater lake. The study focused on cyanobacteria, especially the toxin-producing species Microcystis aeruginosa. These algae thrive in warm, nutrient-rich water and move up and down the water column every day. Using a new model, researchers from FAU’s Harbor Branch Oceanographic Institute and the University of South Florida studied these daily migrations. They found the algae rise in the morning to get sunlight and sink at night due to mixing from cooler temperatures and wind. Wind mainly from the south or southeast pushes the algae toward the northern parts of the lake. This creates visible algae streaks along the northern shores, especially in spring and summer. The model showed that algae concentrations peak late in the morning, then drop in the afternoon. High temperatures encourage algae growth, while strong winds mix the cells below the surface, limiting their access to light. Researchers confirmed the model’s accuracy using water samples, sensors, and satellite images. Results matched field data, showing blooms in the central basin and narrow bands along the northern edge. The study highlights the importance of vertical movement in bloom formation, more than horizontal drift. It also found that temperature and wind are the key drivers of bloom timing and intensity. Lake Okeechobee connects to other water bodies like the Everglades, St. Lucie River, and Caloosahatchee River. Algae blooms in the lake can affect water quality downstream. This research helps improve forecasting and management of harmful algal blooms in Florida’s water systems.