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  • Writer's pictureNancy McAleer

Red Tide - Everything You Need To Know

Red Tide FAQ's

Facts, resources & health information related to red tide.

What to do when an algae bloom hits the shore and how to salvage a vacation on the beach. Specifically this article relates to the Karenia Brevis phytoplankton that forms in the Gulf of Mexico off of Florida, Texas, Alabama, Louisiana, and Mexico.

What is red tide?

Red tide is the common name for a toxic algae bloom formed by a phytoplankton called Karenia Brevis. It forms in the off-shore in the ocean and Gulf of Mexico waters. This type of algae cannot survive in freshwater.

Karen Brevis

How does red tide grow?

Karenia Brevis is commonly present in the Gulf of Mexico. It blooms when water temperatures range between 72 - 82° F and salinities range between 31 - 37% (Steideinger et al. 1998). Sunlight and lack of water nutrients also play a role.


Why is red tide red?

Large concentrations can discolour water giving it a red or brown shade. Water may be discoloured from clear to dark hues.

Red Tide

Where does red tide form?

Red tide is believed to initiate offshore at depth before migrating to the surface. It is a slow developing phytoplankton compared to other phytoplankton species. The wind, currents, and weather are factors in transporting red tide inshore.

P.Schmidt, Charlotte Sun

Does red tide only occur in Florida?

No. Red tide is not a local occurrence. It can be found in other oceanic coastal areas throughout the world produced by different types of phytoplankton (Australia, South America, North America, Asia, etc…)

Recorded incidents of Red Tide

Is red tide a new phenomenon?

No. The first recorded case of Red Tide was in 1530 off the Florida Gulf Coast. According to Florida Wildlife Commission, fish kills near Tampa Bay were included in records of early Spanish explorers. In the 1700’s the first recorded case was in British Columbia, Canada. Other cases have been recorded in the 1800's and the first scientific recording in the U.S.A. was in 1947. It has been monitored and studied by scientists rigorously ever since throughout the world.

How long does red tide last?

A red tide bloom can last a few days, weeks or in rare cases months depending on the environmental conditions that influence the life cycle of an algae algae bloom. Onshore winds bring red tide near the shore and offshore winds drive it out to sea. The dissipation of red tide depends on sunlight, water temperature, nutrients, and water salinity, as well as wind, water currents and the weather. Red tide can dissipate and return towards he end of its life cycle due to these elements.

Clock on Beach

Can red tide live when it's washed up on the beach?

Karenia Brevis is a single celled marine algae which can only survive in marine waters (and has a pretty narrow range of tolerance for things like salinity). However, when waves are crashing onshore, the cells break open allowing the brevetoxin cells produced to become airborne, which is why (when winds are blowing onshore) humans can breathe in the toxins resulting in itchy eyes, runny noses, and scratchy throats.

Can we predict where red tide will occur?

No. Once red tide has been identified its movements can be predicted by monitoring the data. You can access Florida information by visiting Data is taken each Wednesday and Friday or more often in areas of high concentrations. The updated data can help people make decisions regarding their beach activities.

How can I navigate a safe holiday with my family during red tide?

Although we are not experts, we have spoken with the experts at Mote Marine Laboratory and Manatee County to help our guests and visitors safely enjoy a trip to Anna Maria Island during a red tide break-out. There are 3 great digital tools you can use to check daily conditions. is a Mote Marine Laboratory website that conducts daily water samples throughout the state of Florida. This interactive map can help you by zooming into your closest beach and clicking on the map marker. A pop up of the daily samples will appear. The Mote Marine Lab employees instructed us to look at the following criteria:

  1. DATE REPORTED - ensure the date and time are current, the report is posted daily.

  2. FLAG - safety conditions determined by the lifeguard stations. Not specifically red tide related but helps determine safety as well rip currents For more Red Flag and Rip Current information visit our Beach Safety Page here.

  3. WATER COLOR - Red Tide affects water clarity, the more dark it is the more intense red tide is.

  4. RED DRIFT - is not the same thing as red tide.

  5. RESPIRATORY IRRITATION - reported if people have been coughing while on the beach

  6. DEAD FISH - usually related to red tide

  7. WIND DIRECTION - if the wind is blowing inward towards the land, the more opportunity for Karenia Brevis cells to break and become airborne. In our case on Anna Maria Island inland would be towards the east.

  8. SURF - If the surf is choppy and crashing on the beach this also causes Karenia Brevis cells to break and become airborne, causing respiratory irritation.

Example Mote Marine Red Tide Beach Report

The Florida Wildlife Commission has created a new interactive digital map with daily conditions relating to specific presence of the Karenia Brevis algae's daily water samples updated at 5 pm. The legend on the map is very easy to follow by color code of their categories ranging from not present to high concentrations.

FWC Red Tide Current Map Legend

FWC Red Tide Example Map

The Florida Health website is a government agency dedicated to providing health and safety information for the state of Florida. In addition to red tide information this website also provides information about blue-green algae, etc... Their rating system has categories from Good to Poor with associated dates that the samples were taken. you can also view samples on this website. Be sure to check the dates next to the beach location to ensure you are reading up to the minute accurate data. To search for beaches on Anna Maria Island, Click the Manatee County Beaches button found on page 2.

Florida Health Government Beach Report

Are red tides harmful?

Red tides produce toxic chemicals that can affect both marine organisms and humans. Red tides can cause massive fish kills, and mortality in birds and marine mammals who accidentally ingest the algae through grasses and other affected fish. (ie: manatees, dolphins).

Dolphin with fish

What are the health effects of red tide on humans?

Call 1-888-232-8635 for Red Tide Health Questions

Person coughing at the beach

Respiratory Issues: Humans may experience respiratory irritation due to released toxins into the air and wind direction (ie: coughing, tear production, skin irritation, itchy throat). People with severe respiratory issues (ie: asthma) can be especially sensitive to depleted air quality and are advised to avoid beaches with red tide. Check the marine forecast, fewer toxins are in the air when the wind is blowing offshore. Over the counter, antihistamines may decrease symptoms and a particle filter mask may lessen the effects. (

Skin Irritation: If you experience skin irritation and burning eyes while swimming, get out and thoroughly wash with fresh water. Swimming near dead fish is not recommended.


Shellfish Consumption: Commercial seafood and shellfish found in restaurants and grocery stores are safe because it comes from red tide free water and is tested under the Florida Dept. of Agriculture & Consumer Services. To date, all known cases of shellfish poisoning have resulted from illegal, recreational, harvesting activity.

Fish Consumption: It is safe to eat local finfish provided the fish are filleted before eaten. In some cases, some toxins have been found to accumulate in the guts of fish. These areas are disposed of when the fish are filleted. However, do not eat dead or distressed animals, especially in a red tide area.

Cooking & Freezing: Cooking and freezing do not destroy the red tide toxin. The toxin cannot be seen or tasted.

*You can find more links to health resources at the end of this article.

What should fishermen know about red tide?

Do not eat shellfish, mollusks, such as clams or oysters taken from Florida red tide waters as they may contain toxins.

Finfish caught live can be eaten if filleted and washed.

Crustaceans such as shrimp, lobsters, and crabs are safe to eat.

Avoid harvesting dead or distressed animals under any circumstance. (resource: Florida Department of Health)

What are the effects of red tide on pets?

Pets may be affected by the Florida red tide. Consider bringing outdoor pets inside to prevent respiratory irritation. Do not allow pets to play with dead fish or foam that may accumulate on the beach during or after a red tide. If your pet eats dead fish, there is a possibility they may get sick. If your pet swims in the red tide, wash it as soon as possible to avoid consumption through licking their fur.

Is it safe to swim during a Florida red tide?

Mote & Florida Wildlife Commission report that “swimming is safe for most people. However, a Florida red tide can cause some people to suffer skin irritation and burning eyes, and respiratory irritation while in the water. Use common sense. If you are particularly susceptible to irritation from plant products, avoid an area with a red tide bloom. If you experience irritation, get out of the water and thoroughly wash off. Do not swim among dead fish because they can be associated with harmful bacteria.”

How can red tides be controlled?

Red tides are a naturally occurring phenomenon and cannot be controlled at the moment due to the following issues:

toxins are released when Karenia Brevis dies

toxins are released into the water environment and air

control strategies must not harm the environment

some red tides are huge (over 10,000 square miles)

red tides exist from the seafloor to the water’s surface

How do the effects of red tide get cleared up?

In Florida, beach sweepers are used to remove dead fish washed ashore. Due to the lifespan of a red tide bloom clean up efforts may take weeks to accomplish.

What else can I do if I can’t go to the beach?

Don't let a little red tide affect your vacation. There are lots of other things to do besides hitting the beach on a sunny vacation. Here are a few ideas:


  • Try renting or chartering a boat and head to other local islands, waterways and bay beaches that are unaffected by the red tide bloom

  • Visit one of the inland preserves to walk, run, bike, kayak, bird watch, and more

  • Shop the local boutiques and businesses who specialize in activities for indoors (ie: painting parties, wine tastings, etc..)

  • Try kayaking or SUP boarding in the Intercostal waterways that are unaffected

  • Monitor the wind direction to schedule your time on the beach. Enjoy the outdoors when the wind is blowing offshore (towards the sea). Click on NOAA for current USA weather forecasts.

  • Visit local attractions that are indoors like aquariums, movie theatres, and art galleries

  • Visit local wildlife and rehabilitation attractions (i.e.: sea turtle talks, wildlife rescue facilities)

  • Get active outdoors by playing tennis, golf, putting courses, skateboard parks, bocce ball, adventure and obstacle courses that are outside the reach of the airborne toxins

  • Find other activities that you can enjoy away from the bloom area, like shopping, mini-golf, flyboarding, horseback riding, jet skiing, and boat charters in areas not affected by the red tide, etc..

  • Check out the local community center to see what activities are scheduled

  • Seek out any local events for flea markets, festivals and more to enjoy

Red Tide doesn't have to ruin your visit to the beach, in fact it may give you a new appreciation for the area you are visiting. There are so many more things to explore than just visiting the shore in a beach town. Be adventurous and peel back the layers to enjoy and explore your favourite coast.

Looking for more information on the Florida Gulf Coast? Check out our 101 Things to Do Away from the Beach to save your vacation from Red Tide. Packed with insider tips and information about Anna Maria Island, Florida. If you liked this article feel free to share it using the social media buttons below.

101 Things to Do Away from the Beach - Anna Maria Island

Links to more health and safety information on harmful algae:

Centers for Disease Control and Prevention:

Florida Department of Health:

Florida Department of Agriculture and Consumer Services:


Disclaimer: This article was written with the cited government resources and contacts with the government and Mote Marine Laboratory agencies in order to provide guests and visitors with credible information to help stay safe while visiting Florida. We are not experts nor do we claim to be. Use the resources provided within the article to make informed decisions. Anna Maria Island Home Rental and/or its Owners, shall not be liable to guests or to any visiting party for any health reactions, injury or death to persons from any cause whatsoever: guests shall indemnify and hold harmless Anna Maria Island Home Rental and/or it's Owners, from any and against all liabilities, claims, expenses, fees, loss of use of actions of any and any kind arising out of renters or their guests using this article as a guide. The Owners/ Management Company is not responsible for accidents, injury, or death of any kind.

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