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Abstract
Harmful algal blooms (HABs) are a phenomenon that occur on Florida’s coast when the dominant algae species overpopulate the area under certain conditions. In recent years, these HAB events have been increasing in frequency and extremity due to multiple factors that are explored in this study. The factors that determine HAB growth are nutrients, temperature, salinity, and flow rate. We focused on the algae species Karenia brevis which is commonly known to cause Florida’s “red tide.” This species is especially harmful because of its mixotrophic nature, size, and toxicity. K. brevis HABs on the West Florida Shelf (WFS) are the worst in the entire United States. The goal of this study is to dive into the factors that make WFS prone to so many K. brevis HABs for extended periods of time. One of the worst HABs in Florida was in 2005, which is our year of study. Satellite data from Aqua MODIS was analyzed to determine the area of the HAB, nutrient and river discharge rate data was used to show one way K. brevis gets nutrients, and ArcGIS Pro was used to plot nutrient pollution hot spots. Other sources such as multiple NOAA and U.S. military sites were used to look at the temperature, salinity, and flow rate. Our remote sensing results lined up spatially and temporally with the in-situ data and the percent frequency data is similar to other K. brevis bloom studies for 2005. Mapped point and non-point sources showed that the nutrient pollution hotspots are the streams flowing into and out of Lake Okeechobee along with the Tampa area. The intense hurricane season increased the precipitation which then led to more runoff and nutrient pollution in the ocean. A large, longlasting HAB peak followed shortly after the hurricane season. By analyzing the other factors that influence HAB growth, we found that they are within the optimal range for K. brevis the majority of the year.