Red tide bloom lasts summer, more common than 50 years ago

An intense and widespread red tide, which appeared to recede after Hurricane Ida, is now spreading from the Panhandle to Charlotte County; and with red tide blooms being stronger than they were just 50 years ago, summer blooms may become more common.

Although the red tide (Karenia brevis) the season is from October to February, blooms are possible during the hottest summer months.

Some scientists say that although red tide occurs naturally in the eastern Gulf of Mexico, modern blooms are unnatural because they are fueled by man-made nutrient sources like agriculture and urban development.

“They’re more prevalent in late summer and fall, but we’ve had a red tide every month of the year,” said Larry Brand, a professor and researcher at the University of Miami. “Some years we have hardly any red tide, although it is becoming increasingly rare. And we don’t really understand that.”

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Summer red tides have been recorded for several decades and some blooms last for more than a year.

“I argue it’s because of the nutrients coming from land runoff with our rainy season,” Brand said. “Last fall (the US Army Corps of Engineers) released water from Lake Okeechobee, and soon there was a red tide at the mouth of the Caloosahatchee.”

This flowering lingered for almost a year, sometimes very intense.

Fish kills and respiratory irritation in humans can occur when levels reach 100,000 cells per litre. Measurements over the past year along Florida’s west coast have been 1 million cells per liter and higher.

The latest from the FWC report shows high concentrations in Clearwater and off Charlotte County.

A fisherman jumps a tarpon in the Tampa Bay area, where a recent red tide has rebounded.

One million cells per liter is the top of the Florida Fish and Wildlife Conservation Commission’s scale, although the number can reach 100 million and more.

Brand says excess nutrients are the cause of longer lasting and stronger flowers.

“You saw it with Piney Point,” Brand said. “Go back 50 years, in general, they tend to last longer and they are more abundant overall. To get a more abundant red tide, you need to have more nutrients.”

In March, a leak occurred at the Piney Point phosphate mine and fertilizer plant, polluting the nearby waterway.

Brand said the nutrient injection helped fuel the red tide bloom off Manatee County, which has been the focal point of the recent bloom.

The average red tide abundance here is 15 times what it was 50 years ago, Brand said.

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“What happened was a tremendous increase in population growth,” Brand said. “(Flowers) are getting denser than before and that’s because of more nutrients. If I want to grow more algae, I need more nutrients. There’s no doubt about that.”

Chris Simoniello, with a research scientist at Texas A&M who is also with the Gulf of Mexico Coastal Ocean Observing Systemrecently helped develop a website that gives red tide updates every three hours.

“We’ve been watching Clearwater south of Sarasota, and the last few weeks have been pretty intense,” Simoniello said. beach and see orange and red.”

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While the FWC report shows average conditions over an eight-day period, the Coastal Ocean Observing System is updated more than eight times a day.

“It’s very low in begging,” she said. “And it’s moderate to high at the south end of Tampa Bay, and south of there it’s in the blue.”

Blue is the color used when only normal background traces are found.

Jim Beever, a retired biologist and climate change planning expert, said red tides have occurred in previous summers, the global phenomenon is nothing new.

“There was one in the begging in 1947,” Beever said. “In 1994 and 1995, there was a two-year red tide bloom, eclipsing the 40-year record of sustained episodes. Then in 1996, after a brief respite, the red tide returned to the Gulf in January and, in a month stretches from Pinellas County almost to Key West.”

Beever agreed with Brand, saying red tides are stronger than they were half a century ago and humans are to blame.

“More frequent, intense and longer blooms have occurred in the Lee County area with poor management of Lake Okeechobee flows,” Beever said. “And don’t forget that the Glades and Hendry county watersheds are also contributing more nutrients as more land has been converted from native habitat and range to other land uses. “

Connect with this reporter: @ChadEugene on Twitter.

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