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2017-2018 Florida Red Tide Determined by Ocean Circulation

Published on: 04/18/2019
Primary Contact(s): quay.dortch@noaa.gov

A composite of all observations of Karenia brevis made by the Florida Wildlife Research Institute from 1953 through 2007. The white ellipse denotes the hypothesized, mid-shelf initiation region. The arrows denote the transport pathways between initiation and manifestation within the epicenter region and along the Florida Panhandle. Credit. R. Weisberg, USF.

New sponsored research from NCCOS shows that the devastating 2017-2018 red tide along the west coast of Florida originated offshore in the mid-West Florida Shelf west of Tampa Bay.

Cells of Karenia brevis, the Florida red tide, were transported along the bottom by upwelling circulation to the Florida shoreline “epicenter” between the Tampa Bay and Charlotte Harbor estuaries. The 2018 bloom was very intense due to cells lingering from the previous 2017 bloom mixing with cells transported from offshore.

Although earlier red tide research supported the belief that red tides originated offshore in the west Florida continental shelf in nutrient poor waters, new NCCOS sponsored research using a robotic underwater glider confirms this hypothesis. Dr. Robert Weisberg of the University of South Florida deployed the glider to map water properties over the region. Applying the glider-derived oceanographic data to a numerical ocean circulation model that calculates particle (i.e., red tide cell) trajectory accounted for the cell distribution in the epicenter region (Tampa Bay to Charlotte Harbor), along the Florida Panhandle coast, and along Florida’s east coast in 2018.

Modeled particle trajectories along the glider track from August 24th 2018 to September 17th 2018 and run through October 1st 2018, a total of 2 to 5 weeks. The initial vertical location for all of these particles was the near bottom level, and the daily color-coding provides the actual depth en route. Credit R. Weisberg, USF.

Conditions are most conducive for a major red tide event when there is a medium amount of upwelling of deeper water along the coast.  If there is too much upwelling, other organisms bloom and if there is too little upwelling, no organisms bloom. Thus, water conditions conducive for a red tide bloom to occur (or not to occur) are determined by the ocean circulation.

The robotic glider used to track water properties for the study. Credit. USF College of Marine Science.

This research was funded in part through the NCCOS sponsored Prevention, Control, and Mitigation of Harmful Algal Blooms (PCMHAB) project “Seasonal Forecasting of Karenia brevis Blooms in the Eastern Gulf of Mexico.”

Learn more from University of South Florida “Red Tide Forensics: So THAT’s What Happened.”

Citation: Weisberg, Robert H., Yonggang Liu, Chad Lembke, Chuanmin Hu, Katherine Hubbard, and  Mathew Garrett. 2019. The Coastal Ocean Circulation Influence on the 2018 West Florida Shelf K. brevis Red Tide Bloom. Journal of Geophysical Research: Oceans https://doi.org/10.1029/2018JC014887

For more information, contact Quay Dortch.

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