Red tide study documents severity of blooms to identify risk levels during future outbreaks

Based more than 60 years of red tide data, one researcher thinks the toxic blooms are lasting longer and that climate change may exacerbate the occurrences.

A recent study uses six decades of red tide data along Florida's west coast to compare the strength of the algal blooms over the years, creating a Bloom Severity Index.

National and regional scientists reviewed cell counts of the organism that causes red tide, Karenia brevis, between 1953 and 2019, along with respiratory irritation reports starting in 2006.

The paper recently published in the peer-review journal PLOS One, shows that red tide blooms most frequently occur from Sanibel Island to Tampa Bay between September and January, typically forming in August and continue through the winter, with October and November being the months most frequently impacted.

“Red tide blooms are described as hitting Southwest Florida nine of every 10 years,” said the study’s lead author Richard Stumpf, oceanographer with NOAA-NCCOS in a press release.

“But not all blooms are created equal. Some last longer, some cause more respiratory irritation. Others affect a smaller area or produce less irritation. In trying to protect public health and local economies, we found that we really needed a better way to gauge blooms and how much of a threat they pose.”