It can make you cough and it kills fish. Here are nine things to know about red tide

We’re answering some of your biggest questions about red tide, which has been reported off Longboat Key, as well as in Tampa Bay off Pinellas and Hillsborough counties. Also, the dumping of hundreds of millions of gallons of contaminated water from Piney Point into Tampa Bay near Port Manatee has raised concerns it will cause a bloom of red tide or other harmful algae.

What is red tide?

According to the Florida Fish and Wildlife Conservation Commission: “A red tide, or harmful algal bloom, is a higher-than-normal concentration of a microscopic algae (plantlike organism). In Florida and the Gulf of Mexico, the species that causes most red tides is Karenia brevis, often abbreviated as K. brevis. To distinguish K. brevis blooms from red tides caused by other species of algae, researchers in Florida call the former the ‘Florida red tide.’ ”

Many red tides produce toxic chemicals, and the organism specific to Florida’s red tide has toxins that affect the central nervous system of fish, which kills them. Waves break open the organism cells and send them into the air, and that can affect humans’ respiratory systems, mostly just an irritation. Pets can also be affected, and the FWC suggests bringing them inside during blooms and not letting them swim in red tide waters or play with dead fish.

It’s not new: “Red tides were documented in the southern Gulf of Mexico as far back as the 1700s and along Florida’s Gulf coast in the 1840s,” according to FWC.

Mote Marine Laboratory and its partners have monitored for Florida red tide from October 2017 through July 2018.

What causes red tide?

Red tide is caused by the algae bloom. Its occurrence can’t be predicted, but scientists can forecast its movement, according to FWC.

Red tide needs three components to form a bloom. First the organism must be present in the water. Second is the correct chemistry — the nutrients that it needs to grow. Third is that physical conditions have to be right in order to concentrate and transport the microscopic algae, according to Mote Marine Laboratory.

What are the effects of red tide?

Red or brown-green water color, dead fish washed up onto the shore, odor of dead fish and respiratory irritation.

Those with underlying chronic respiratory problems such as asthma should avoid red tide areas, according to Mote. You can wear a mask to cover your nose and mouth if you notice you are experiencing symptoms.

Why is red tide harmful?

Red tide produces brevetoxins that can affect the central nervous system of fish and other vertebrates, often causing death, Mote researchers say. Waves can break open the organism’s cells and release those toxins into the air, leading to respiratory irritation.

Where is it?

Varying of the red tide organism, Karenia brevis, are present in lower Tampa Bay near Port Manatee and in the Terra Ceia Aquatic Preserve, as well as off Pinellas and Hillsborough counties, according to the Florida Fish and Wildlife Conservation Commission.

It also has been found off beachs in southern Sarasota County and near the south end of Longboat Key.

How long will it last?

The short answer is, we don’t know. Red tides can go on for a few weeks or longer than a year, according to researchers. How long a bloom will last depends on physical and biological conditions as well as the wind and water currents.

Blooms can also subside and reoccur.

Is it safe to swim?

According to the FWC, it’s safe for most people to swim, but definitely not around dead fish. There can be irritation to skin, eyes and the respiratory system. If someone swimming does experience signs of irritation from red tide, get out of the water and wash off.

Also, don’t allow your pets to play with dead fish or foam on the beach. Wash them as soon as possible if they happen to swim in red tide waters.

Has dumping of waste water from Piney Point made it worse?

Environmentalists worry that nutrient-rich water from Piney Point could mix with the red tide, fueling an explosive growth of the bloom.

What is being done?

As of now, there is no practical way to control or kill the blooms, according to FWC. Any potential control methods would have to kill the organism and get the toxins it produces out of the water without harming the environment. So far, nothing has worked.

Mote, however, is developing and assessing different technologies.

For more information on red tide, visit myFWC.org.research/redtide and Mote.org.

This story was originally published April 21, 2021 at 1:33 PM.