Florida Red Tide: Overview, Causes, & Effects

By Erin Blakely of Erin’s Travel Tips

Florida’s unique biological and environmental terrain faces a continuous threat from a naturally occurring but disruptive phenomenon known as the Florida red tide. Famed for its endless sunshine and picturesque beach getaways, the Sunshine State harbors a less pleasant aspect that can disrupt even the most idyllic vacation. 

In this article, we will delve into the complexities of red tide, exploring its underlying causes and its extensive impact on both the natural environment and human activities.

What Exactly Is Red Tide?

Red tide is a common name for a type of harmful algal bloom (HAB) caused by an overgrowth or “bloom” of microscopic algae in the water. The term “red tide” comes from the reddish or brownish color that water can turn due to the high concentration of algae. However, the water doesn’t always turn reddish during a bloom. This depends on the severity.  

Red tide conditions can range from:

  • Non-present
  • Very low
  • Low
  • Medium
  • High

One of the most well-known red tide-causing species is Karenia Brevis (K. brevis), which is prevalent in the Gulf of Mexico and along Florida’s coast. Red tide toxins can have a devastating impact on marine life and pose potential health risks for humans. 

Florida Red Tide: Beach at sunset
Clearwater Beach, Florida

Causes: What Triggers Florida Red Tide?

The mechanisms driving the proliferation of red tides are still under scientific scrutiny, but it’s known that they often form many miles offshore. Conditions such as sunlight, nutrients in the water, and salinity affect their growth and concentration. Once formed, wind and water currents can carry these blooms closer to the shoreline.

Red Tide has occurred for centuries, and even before human settlement. There is no current proof that nutrient pollution is the cause of K. brevis blooms.

Effects of Florida Red Tide

Local Human Health

Florida red tides can harm human health. The brevetoxins produced by K. brevis can lead to respiratory issues when carried ashore by wind and waves, severely affecting individuals with pre-existing conditions such as asthma or COPD. 

Local Animals

Red tide also poses a risk to land creatures such as shorebirds. They consume fish contaminated by red tide toxins, resulting in side effects including inability to fly, seizures, and other harmful effects.

Plant Life

While red tides do not directly impact terrestrial plants, they pose a significant threat to aquatic vegetation. The dense algal blooms can block sunlight causing a decline in aquatic plant life, affecting the overall marine ecosystem.

Marine Life

Red tide toxins can have devastating effects on marine life. Fish, dolphins, manatees, and sea turtles may result in mass mortality along with other marine creatures. The decline in aquatic plants and toxic fish, poses survival challenges for herbivores and their predators.

These effects of Florida red tide are far-reaching and interconnected, stressing the need for careful monitoring and proactive management strategies.

Effects of Florida Red Tide on Businesses & Tourism 

While red tide doesn’t stop Florida from being a fantastic place to visit, it can certainly put a dent in its tourist appeal near the coastline. Red tide effects reach far beyond the scope of dead fish. Health advisories can deter tourists, leading to quieter beaches and fewer customers for local businesses like hotels, restaurants, and shops. While vacationers may only partially cancel their vacations, they may change their plans to indoor activities or visit Florida cities further inland.

Fishing activities and water sports can also take a hit because of dead fish and potential water irritation. This is a prominent issue for those that stay near shore. Most commercial businesses and charters tend to fish at least a few miles offshore, which helps keep their businesses afloat. However, additional issues persist when red tide impacts the habitat conditions affecting the local aquaculture including protected species.

Florida Red Tide: Looking at the water's surface, plants and fungal life visible below
St Petersburg, Florida

Common Beaches to Have Florida Red Tide Outbreaks

While red tide most commonly affects Florida’s Gulf Coast beaches, it does also occur in other areas. 

Southwest Florida Coast

This region is particularly prone to red tide events. The coastlines of Pinellas, Hillsborough, Lee, Collier, Charlotte, Sarasota, and Manatee counties often experience red tide, with popular beaches such as Fort Myers Beach, Sanibel Island, St. Pete Beach, Clearwater Beach, Venice Beach, Siesta Key, and Bradenton Beach have been impacted over the years. 

Florida Northwest Coast

The Florida Panhandle has some of the most beautiful and clear emerald green water in Florida. At times these beaches in counties like Escambia, Santa Rosa, Okaloosa, and Bay, can also experience red tide. Red tide also affects counties to the south such as Franklin, Dixie, Levy, and areas along the coastline.

Florida’s East Coast – Atlantic Ocean

Red tide outbreaks are rarer on Florida’s East Coast, but when they do happen in coastal counties like Brevard, Indian River, St. Lucie, Martin, and Palm Beach.

How do you know if a beach has red tide?

When you’re planning a beach day in Florida, it’s a good idea to be aware if there is a red tide outbreak. The most reliable way to know for sure is to check with the experts. The Florida Fish and Wildlife Conservation Commission (FWC) keeps track of red tide conditions and provides daily updates.

You can also detect signs of red tide from changes in the water color to a reddish-brown instead of its usual blue-green color. You may notice more dead fish along the shoreline, or experience respiratory issues such as difficulty breathing or an irritated throat. The smell at times can be overwhelming depending on the severity level.

Is it safe to swim in red tide?

No, it’s not recommended to swim in red tide because of the toxins that can lead to skin irritation, burning, trouble breathing, and sore eyes. It’s important to monitor local updates and advisories before deciding to swim during a red tide event.

Florida Red Tide: A boat sailing across the water
St Petersburg, Florida

Frequently Asked Questions

Why does red tide smell?

The red tide smell is mainly due to dead sea life. The red tide’s toxins can kill off lots of marine creatures, and when they start decaying, it creates a strong, unpleasant odor. The algae causing red tide can also add a bit of a fishy smell. Plus, the toxins from these algae can mix with the air, especially when it’s windy, possibly adding to the scent. It’s a distinctive mix that signals a red tide event.

Where is red tide the worst?

Red tide can occur all over the world, but its impact is particularly severe in certain regions. The Gulf Coast of Florida is notorious for persistent and impactful red tide events. This is primarily due to the prevalence of the algae, Karenia brevis, which thrives in the warm waters producing potent toxins. Other states like Maine and California are also known to experience red tide.

How long does a red tide usually last?

The duration of Florida’s red tide could be weeks, months, or even years in particular areas.. A lot of factors come into play here, like the water’s temperature and nutrient levels, or how the wind and currents are moving. In Florida, we usually see red tides kicking off in late summer or fall, and sometimes they hang around until spring. But remember, every red tide is different, so it’s hard to put a fixed timeline on them. Scientists are still figuring out how to predict these events better.

What kills red tide?

Unfortunately, there is no current solution to prevent or kill red tide. However, the University of Central Florida provided evidence that spraying a clay mixture on the water has helped with weighing down the affected algae and dropping it to the ocean floor. 

Red Tide Resources

For more information and to continue reading on Florida red tide, you can visit these helpful resources:

Florida Fish and Wildlife Conservation