Red Tide

By Joyce Kopcik

Red Tide has been in the local news quite a bit lately. What is it? Is it the same as blue-green algae? Is it dangerous? What are some of the symptoms and treatments? How can we monitor it in our area?

What is red tide? Florida red tide forms offshore and is one of several ‘harmful algal blooms’. Although it has been in the news in recent years, showing pictures of fish kill, it is not a new phenomenon, with reports of it as far back as the 1700’s. In high concentrations, it will color the water red, hence its name.

Is red tide the same as blue-green algae? There are two forms of blue-green algae, one that lives in saltwater and another that lives in freshwater. The form that we normally see here in Southwest Florida is the freshwater variety, and it normally occurs in late summer and early fall when the water is hottest. Nutrients that are washed into rivers and canals encourage its growth; consequently, Florida has a fertilizer ban during much of the year. Fresh-water blue-green algae and red tide do not generally mix.

Is red tide dangerous? Red tide is particularly dangerous to marine, and wildlife and can cause neurological damage. Be especially careful with your dogs. Consumption of local seafood can be dangerous; although seafood sold in a restaurant or fish market is safe because the commercial fishing industry is highly regulated and any local seafood is tested to make sure there is no red tide poisoning.

Symptoms related to red tide exposure are breathing problems and eye, nose, or skin irritation.
If you have asthma or other chronic respiratory conditions, you should avoid red tide areas, especially during high onshore winds. Even without chronic conditions, you could experience respiratory irritation. Usually, these symptoms will go away soon after you leave the affected area, but if they do not consult a medical professional. Swimming in red tide can also cause skin irritation and burning eyes. If you experience these symptoms, shower with soap and water.

One of the more serious issues is eating seafood that has been contaminated by red tide, causing shellfish poisoning, which can be life threatening. Symptoms include tingling of the mouth, lips, or tongue, burning, numbness, slurred speech, dizziness, drowsiness, or respiratory paralysis. Additional symptoms could be nausea, diarrhea, or vomiting. Anyone exhibiting these symptoms after consuming local shellfish should seek immediate medical attention.

The best treatment is always prevention and staying away from areas affected by red tide and avoiding the consumption of seafood that may have red tide toxins. If ever in doubt about the severity of any symptoms, consult a medical professional.

For more information about symptoms and treatment, for both you and your dogs, please refer to:

How can we monitor red tide in our area? The Florida Fish and Wildlife Conservation Commission (FWC) provides up-to-date information about red tide conditions at:

Please refer to the FWC’s website before heading out boating or to the beach, to check for local red tide conditions.