CoAuthors

Robert H Weisberg (University of South Florida, United States); Katherine A Hubbard (Florida Fish and Wildlife Conservation Commission - Fish and Wildlife Research Institute, United States)

Blooms of the toxic dinoflagellate Karenia brevis occur frequently on the west coast of Florida, killing fish and other marine life, threatening public health and adversely impacting local economies. Based on analysis of satellite altimetry data, a seasonal prediction tool was developed for the occurrence of major K. brevis harmful algal blooms on the West Florida Shelf (WFS). The seasonal prediction is based on a hypothesis that interactions by the Gulf of Mexico Loop Current with the shelf slope under certain conditions can flush the WFS, change its residence time, and reset nutrient structure in ways that may obviate bloom development. The Self-Organizing Map (SOM), a machine learning technique, is used to identify such Loop Current patterns and their cumulative duration of occurrences from satellite altimetry data. This serves as an indicator of offshore forcing of anomalous upwelling. The presence (or absence) of the anomalous upwelling during the formative season for K. brevis blooms is found to be consistent with the occurrence of (or lack of) severe WFS coastal blooms later in the year. Considering both the hindcasts for years 1993 – 2015 and the forecasts for recent years (2016 – 2022) relative to K. brevis field observations, the seasonal predictor is found to be successful in 25 of 30 years.