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February 14, 2024
Please join us in congratulating Miami Waterkeeper’s Research Coordinator, Elizabeth Kelly, on the publishing of her paper, “Proliferation of microalgae and enterococci in Lake Okeechobee, St. Lucie, and Loxahatchee watersheds."
This study analyzed relationships between microalgae (such as cyanobacteria) and the fecal indicator bacteria (FIB) enterococci. Microalgae blooms and high fecal indicator bacteria levels have been occurring in Florida’s recreational waterways for years. More recently, this has become a management concern as microalgae blooms have been attributed to potentially toxic cyanobacteria, and enterococci exceedances linked to human infection and illness. Since both the microalgal blooms and bacterial exceedances occur in regions that receive managed freshwater releases from Lake Okeechobee, the study hypothesized that both the blooms and exceedances are related to excess nutrients, specifically nitrogen and phosphorus, from the Lake.
Samples were taken at a total of 3 experimental sites: Lake Okeechobee, St. Lucie River, and the Loxahatchee River. The results from this study demonstrated that excess nutrients are associated with elevated chlorophyll A and enterococci levels. Flow, tide, and short-term rainfall influenced the levels of nutrients, chlorophyll A, and enterococci at each site and were site-specific. This may indicate that chlorophyll A and enterococci levels change based on a combination of the available nutrients and the physical-chemical, environmental, and meteorological conditions at each site. Overall findings suggest that both nutrient-rich lake water and untreated surface water runoff contributes to microalgae blooms and enterococci exceedances in southeast Florida.
Future work recommended includes the evaluation of the possible connections between cyanobacteria and enterococci and continued study of the biogeochemistry of areas that have blooms and exceedances. These studies should focus on the nutrients specific to each watershed, as well as the native sediment, organic matter, and local hydrodynamics, including the effects of environmental conditions such as rainfall, and extreme weather conditions such as hurricanes.
Continued study in this area will provide greater understanding as to whether sediments could be contributing to blooms and exceedances in the St. Lucie River, especially after periods of heavy rainfall. An understanding of the influence of weather events on blooms and exceedances may lead to the eventual forecasting of blooms and/or exceedances. This way, relative agencies, and the general public can better prepare prior to these blooming events.
We applaud Dr. Kelly for this important research and publication of findings. Her work will contribute to increased understanding of water management and human health impacts in our state. Read the full study here!