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This is cyanobacteria, usually called blue-green algae — a totally separate problem from red tide.

Capt. Josh:

I am not a scientist, but I am a native and have a few questions about red tide. Why do most people link the red tide problem with the algae problem in Fort Myers? One is fresh water the other in salt water. Red tide rarely gets up into the Harbor. Has there ever been any study to link red tide in the area to beach nourishment projects ? It seems that the last real bad outbreak was shortly after the Fort Myers project, and now after the Stump Pass project. The dredging process brings up sand which is the natural ocean filter system (per my saltwater aquarium). When it is pumped ashore, the water which is rich in bacteria and nutrients, flows back in to the Gulf. Now these organisms are in the surface water with sunlight to feed and grow at a faster than normal rate.

— A. Romanowski

Most people have some confusion about red tide. It’s very understandable why: They get it wrong because the sources their information comes from also get it wrong. The amount of inaccurate, misleading and just plain bad info on red tide and blue-green algae is simply astounding.

Here’s an example from WINK News. They did a story on Sept. 24 about toxins. The headline on their website is “Doctors warn of potential airborne toxins from algae & red tide.” (See the whole story at

Sounds like red tide is creating airborne hazards. But if you read the story, the focus is microcystins — the poisons produced by cyanobacteria (aka blue-green algae), which have nothing whatsoever to do with red tide. So the headline is misleading, and someone who doesn’t understand the technical terms might assume that microcystins are produced by red tide. Also, the story consistently misspells it “microsystins.”

Wait, though; it gets worse. The story references a Florida Atlantic University study, citing that microcystins were found “in 100 percent of people they tested, suggesting the toxins are airborne.”

But there’s no further reference to the study, in which researchers took blood and urine samples and nasal swabs from people who had frequent exposure to the water in the St. Lucie River, Indian River Lagoon or around Lake Okeechobee. Study participants were chosen specifically because of their proximity to waters known to be high in cyanobacteria.

Only nasal swabs have been tested. Blood and urine analyses are not yet available. The study, which hasn’t been published and might not be until next year, also has not drawn any line between the presence of microcystins in the nasal cavity and any type of health problems.

Despite that, the story continues with an interview with Dr. Parisima Taeb, who warns of cancer and then says people are going to die five to 10 years from now.

Now to the average person watching this news story, what’s the takeaway? Algae and red tide are producing poisons which have gotten into all of us. These poisons cause cancer and are going to kill maybe lots of people.

That’s a problem, because it’s wildly inaccurate. Cyanobacteria alone produce microcystins, so the potential problem exists only where these freshwater organisms are in large numbers. The research is not settled on the long-term effects of microcystins on humans. We know that if ingested, the toxins cause liver problems. They are also suspected to be carcinogenic, with liver and testicular cancer deemed most probable. There is no solid basis to say there will be any deaths as a result.

But, I guess that doesn’t get people to watch the news. Sensationalism sells.

So, to your specific questions: The link between red tide and cyanobacteria is largely conflation; that is, people see two things with certain similarities happening and because they don’t understand either, they combine them into one problem. We know they’re both algae, therefore, they’re the same problem.

To further confuse the issue, a marine cyanobacterium called Trichodesmium is actually associated with red tide, because it occurs in the open Gulf and sometimes its blooms precede red tide outbreaks.

The second question is interesting in that your own observations are probably leading you down the wrong path. What happens in an aquarium environment and what happens in the wild ecosystems are vastly different things.

Sand and gravel are frequently used in aquarium filtration because if you constantly pass oxygenated water through them, aerobic bacteria will colonize the surface of the grains. These beneficial bacteria will feed on ammonia and ammonium, breaking them down into nitrites and ultimately nitrates.

In the wild, these bacteria are much less common, mostly because the biomass of fish and other marine life per gallon is far less in the ocean versus an aquarium. And the bacteria don’t colonize sand heavily because they need oxygen, and little water flows though most sandy bottoms (the surf zone is an exception).

In both questions, the real problem is having some information but not quite enough. It’s like piecing together a puzzle, but not only are half the pieces missing, the ones available are all the same shape and the box with the picture has been mislaid. It’s intensely frustrating for everyone who’s trying to understand.

The best thing I can tell you is do your own research, preferably not on social media, and never believe that you can get the whole story in three minutes or less.


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