Occurrence and Spatial Extent of HABs on the West Florida Shelf 2002–Present

Harmful algal blooms (HABs) can lead to severe economic and ecological impacts in coastal areas and can threaten marine life and human health. About three quarters of these toxic blooms are caused by dinoflagellate species. One dinoflagellate species, i.e., Karenia brevis, blooms nearly every year in the Gulf of Mexico, particularly on the West Florida Shelf (WFS), where these blooms cause millions of dollars in socioeconomic damage. In this letter, we use the red band difference (RBD) bloom detection technique for detection of low backscattering phytoplankton blooms, such as K. brevis, and conduct time-series analyses of the spatial extent of these blooms using Moderate Resolution Imaging Spectroradiometer (MODIS) monthly mean data spanning July 2002 (sensor inception) to September 2014. The time-series results show that the RBD successfully detects the documented HABs in the region, illustrating the seasonal and interannual variability, including the extensive blooms of 2005 and 2014.