What’s Up with the Red Tide in the Panhandle?

What’s Up with the Red Tide in the Panhandle?

Red Tide has been a persistent presence in the Panhandle since September and responsible for many reported fish kills and respiratory distress in some people.  Over the past week, red tide was still present in low to medium concentrations in or offshore of Escambia County to Bay County.

This is a picture of a dead 4-inch striped Jack-knife fish, killed by red tide, laying next to a clump of sargassum on the beach in Miramar Beach, Florida.

Jack-knife fish killed by red tide Miramar Beach, Florida

Red tide is a natural occurrence and Florida experienced red tides long before humans settled here.  The tides originate 10-40 miles off shore and winds and currents bring them inshore.  Red tide is fueled by nutrient typically stemming from land-based runoff.

During winter, the northerly winds and southbound currents will push the tide back offshore.  There was hope that Hurricane Michael might help carry the red tide back out to sea. Unfortunately, it seems the nutrient run-off from the storm’s heavy rain or retreating storm surge may have contributed to the intensity and duration of the bloom.

In our economy, which is heavily dependent on tourism, the red tide is continuing to take a toll, especially on waterfront businesses.  According to the Florida Fish and Wildlife Conservation Commission, store-bought and restaurant served shellfish are safe to eat during a red tide bloom because shellfish are monitored for safety and tested for red tide toxins before they are sold. The edible parts of crabs, shrimp and fish are not affected by the red tide organism and can be eaten, but guts should be discarded.

Many remember the local red tide bloom in 2015.  The longest red tide bloom ever recorded lasted 30 months from 1994 to 1997.  Warmer water due to climate change is predicted to cause algae to bloom more often, more intensely, and in more water bodies. It is imperative that we reduce nutrient inputs to our lakes, rivers, estuaries and coastal ocean waters today.

Who is the Creature That Causes Red Tide: Information on Karenia brevis

Who is the Creature That Causes Red Tide: Information on Karenia brevis

When I was in high school we were required to take a semester of communism during our senior year – the idea was to “know the enemy”. That is what we plan to do here… But, the enemy is a microscopic plant.


Its name is Karenia brevis.  It is one of about 10 species of Karenia found in the ocean but it is the dominant form in the Gulf of Mexico. Karenia is referred to as “phytoplankton”, which suggests it is a microscopic plant.  But in fact, it is in the Kingdom Protisita, not Plantae.

The dinoflagellate Karenia brevis.
Photo: Smithsonian Marine Station-Ft. Pierce FL

It is “plant-like” in that it has chlorophyll and can produce its own food. It differs in that it is a single cell.  They are a type of phytoplankton called “dinoflagellates” because they have two flagella.  The next question of course is what is flagella?  It is a hair-like structure used by the cells for location.  Though they can swim, they cannot out swim a current and so drift in the ocean – using their flagella to move up and down within the current and orient themselves.


The cell is covered with a protective shell called a theca, which as grooves, known as girdles, in which the flagella lie – one running east-west, the other north-south. They are between 18-45 microns long with the north-south flagella extending to look like a tail.  They are members of the Gulf of Mexico community.  Always out there, always have been.  Typically, a plankton sample might find 1000 cells / liter.  At these concentrations there does not seem to be a problem.


A problem?

What’s the problem?


The problem is that in its defense, K. brevis will release toxins.  The toxin is a cocktail of lipophilic polyether compounds called brevotoxins.  At low, or background concentrations, the levels of brevotoxins does not seem to effect marine organisms much at all.  However, when the population of cells increases, to say 2 million / liter, fish kills can occur.  The state of Florida will close shellfish harvesting if the concentrations reach 5000 / liter.


This brevotoxin is pretty strong stuff. It effects the nervous and immune systems, and effects the respiratory system.  For marine vertebrates, it is deadly.  At concentrations over 1,000,000 cells / liter, it can cause death for fish, dolphins, sea turtles, and manatees.  Shellfish are filter feeders.  During large blooms of K. brevis shellfish can consume enough to make humans very sick if they consume the shellfish.


So what causes their numbers to increase from 1000 to 1,000,000 cells / liter?



Though K. brevis is not a plant, it is plant-like.  Plants like sunlight and fertilizers.  Warm shallow seas of southwest Florida are perfect.  Nutrients are available in the environment and growth begins.  Most blooms (large growth spurts) occur offshore.  They love high salinities and not as common in our estuaries.  However, they are plankton – wind and currents can move them closer to shore.  During the raining season (summer) run-off from land brings with it nitrogen and phosphorus (nutrients) which can enhance a bloom.  The fish kills begin, the respiratory problems for humans are annoying, and the tourist become concerned.  Red tide can certainly have an impact on the local economy.


Globally, algal blooms seem to be increasing. Red tide can last a few days or a few months, each year varies.  These are not exotic species; they are local Gulf residents who are finding warmer, saltier seas that they love.  Algal blooms typically occur from September to February and though are common in southwest Florida, can extend across the Gulf to Texas – which the Florida panhandle is experiencing currently.


As Dr. Karl Havens mentions in his article attached, we cannot control the weather, but we can control the amount of nutrients we allow into our waterways. We should consider management practices that do just this to reduce the effects of these naturally occurring blooms.


Below are other articles from Sea Grant on this topic.


Frequently Asked Questions About the 2018 Red Tide Bloom – Betty Staugler, Florida Sea Grant



Understanding Florida’s Red Tide – Betty Staugler, Florida Sea Grant



Watching and Waiting: Uncertainty About When the Algal Blooms Will End – Dr. Karl Haven, Florida Sea Grant






About Florida Red Tides. Florida Fish and Wildlife Conservation Commission. http://myfwc.com/research/redtide/general/about/.


Indian River Lagoon Species Inventory. Karenia brevis. Smithsonian Marine Station at Ft. Pierce.  http://www.sms.si.edu/irlspec/Kareni_brevis.htm.


Pierce, R.H., M.S. Henry. 2008. Harmful Algal Toxins of the Florida Red Tide (Karenia brevis): natural chemical stressors in South Florida coastal ecosystems. Ecotoxicology. 17(7). Pp. 623-631. http://www.sms.si.edu/irlspec/Kareni_brevis.htm.

Exploring the Gulf of Mexico: Phytoplankton Part 2

Exploring the Gulf of Mexico: Phytoplankton Part 2

In the last article, we discussed what phytoplankton are, what their needs were, and their importance to marine life throughout the Gulf and coastal estuaries. In this article, we will discuss the different types of phytoplankton found in our waters.

The spherical shape of the centric diatom.
Image: Florida International University

Marine scientists interested in the diversity and abundance of phytoplankton will typically sample using a plankton net. There are a variety of different shapes and sizes of these nets, but the basic design would be funnel shaped with a sample jar attached at the small end of the funnel.  The plankton net would be towed behind the research vessel at varying depths for a set period of time.  All plankton collected would be analyzed via a microscope.  According to the text Identifying Marine Phytoplankton (1997) there are at least 14,000 species of phytoplankton and some suggest as many as 120,000. Most of these, 12,000-100,000, are diatoms, one of five classes of marine phytoplankton.  The majority of the phytoplankton fall into one of two class, the diatoms and the dinoflagellates.


Diatoms are typically single celled algae encased in a clear silica shell called a frustule. The frustule can come in a variety of shapes, with or without spines, and many resemble snowflakes – their quite beautiful.  They are found in the bay and Gulf in great numbers, as many as 40,000,000 cells / cup of seawater.  They are the dominate phytoplankton in colder waters and are most abundant near upwellings.  These are the “grasses of the sea” and the base of many marine food webs.  When diatoms die, their silica shells sink to the seafloor forming layers of diatomaceous earth, which is used in filters for aquariums and oxygen mask in hospitals.


Dinoflagellates differ from diatoms in that they produce two flagella, small hair-like projections from the algae that are used for generating water currents and movement. Their shells are not silica but layers of membranes and are called thecas.  Some membranes are empty and others contain different types of polysaccharides.  Dinoflagellates are more abundant than diatoms in warmer waters.  There are about 2000 species of them.  One type, Noctiluca, are responsible for what locals call “phosphorus” or bioluminescence.  These dinoflagellates produce a blue-ish light when disturbed.  Many see this when walking the beach at night.  Their footprints glow for a few seconds.  At night, boaters can see this as their prop wash turns the dinoflagellates in the water column.  The bioluminescence is more pronounced in the warm summer months and is believed to be defense against predation.  The light is referred to as “cool” light in that the majority of the energy is used in producing light, not lost as heat as with typical incandescent bulbs – hence the birth of the LED light industry.

The dinoflagellate Karenia brevis.
Photo: Smithsonian Marine Station-Ft. Pierce FL

Several dinoflagellates produce toxins as a defense. Some generate what we call red tides.  In the Gulf of Mexico, Karenia brevis is the species most responsible for red tide.  Red tides typical form offshore and are blown into coastal areas via wind and currents.  They are common off the coast of southwest Florida but occur occasionally in the panhandle.  Many local red tides are actually formed in southwest Florida and pushed northward via currents.  Red tides are known to kill marine mammals and fish, as well as closing areas for shellfish harvesting.


Like true plants, phytoplankton conduct photosynthesis. Between the diatoms and dinoflagellates, 50% of the planet’s oxygen is produced.  These are truly important players in the ecology of both the open Gulf and local bays.





Annett, A.L., D.S. Carson, X. Crosta, A. Clarke, R.S. Ganeshram. 2010. Seasonal Progression of Diatom

Assemblages in Surface Waters of Ryder Bay, Antarctica. Polar Biology vol 33. Pp. 13-29.


Hasle, G.R., E.E. Syvertsen. 1997. Identifying Marine Phytoplankton. Academic Press Harcourt Brace and

Company. San Diego CA. edited by C.R. Tomas.  Pp. 858.


Steidinger, K.A., K. Tangen. 1997. Identifying Marine Phytoplankton. Academic Press Harcourt Brace and

Company. San Diego CA. edited by C.R. Tomas.  Pp. 858.

When Will the Red Tide End?

When Will the Red Tide End?

This is a question I have been asked several times in the last week. As most of you know the red tide that has been occurring off the panhandle the last few months is still around. Dead fish were reported on Pensacola Beach again the weekend of Dec 12-13 and a few people said they were having eye and throat problems. This weekend I received a call of dead fish inside the bay but the caller was not suffering from eye and throat issues. Its December… what’s going on?

The dinoflagellate Karenia brevis.   Photo: Smithsonian Marine Station-Ft. Pierce FL

The dinoflagellate Karenia brevis.
Photo: Smithsonian Marine Station-Ft. Pierce FL

Well let’s look again at what red tide is and what facilitates the bloom. Red tide is caused by small microscopic plants called dinoflagellates. Dinoflagellates, like all plants, develop defense against herbivores that may try and feed on them. A few of these dinoflagellates release toxins when disturbed as a defense. They are in the Gulf all of the time but usually in low numbers, maybe 300 cells per liter of water, and cause no problems. But when conditions favor growth and reproduction they do just that – grow and reproduce – in great numbers, maybe 3000 cells per liter. When this happens the water actually darkens with their presence and the amount of toxin they release increases due to the increase number of cells – now marine creatures other than those that feed on them are impacted by the toxin – this is a red tide.


So, what are these conditions?

Well, like all plants dinoflagellates like sunlight, warm temperatures, and nutrients (fertilizers). So you would think that these blooms would occur when most plants grow – summer… and you would be right. There is another condition that contributes and those are currents. If currents are strong it will spread the bloom and the concentrations are spread as well, lowering the concentration per liter of water and thus reducing or diminishing the red tide.


We generally have plenty of sunshine here in the panhandle – temperatures are relatively warm, though they are warmer in south Florida – and there are nutrients. Nutrients are available naturally in the Gulf but are increased when we have a lot of rain as the runoff brings nutrients from land. But remember red tides are not always the result of human pollution – they occur naturally but can be increased or extended with excess nutrients from human runoff. The currents here along the panhandle tend to keep red tides at bay most of the time – we do not see them often here, but that is not the case with southwest Florida. In the Port Charlotte area red tides are more common part of life. It is warmer, there is more agriculture and municipal nutrients entering the Gulf, and the currents there are slower/weaker than we have here.


So what is up in the panhandle this year?

Well the sun is still shining! Feels great out there actually. The water temperatures were in the upper 60’s inside Pensacola Bay this week and that is typical, but the Gulf is still in the 70’s, and that is typical as well. What is not typical is the warmer air temperatures. This will slow the temperature drop of the Gulf and allow plants to extend their non-dormant season. H2O is a polar molecule (has an electric charge) and so the molecules are bonded together like two magnets. Because of this it takes more heat (energy) to warm the water and so area waters warm at a slower rate than the air. If the air temperatures remain warm it will be longer before the Gulf cools down. These warmer temperatures may extend the red tide a bit longer. As far as nutrients, heavy rains in October and November probably supplied more food for the plants and contributed to the beginning of the tide. Currents pushed the red tide inshore where we began to experience the eye problems and fish kills. The north winds from the recent fronts passing through may generate upwellings in the Gulf. Upwellings are currents that bring water from the ocean floor to the surface, this would bring nutrients with it. So we still have sun, warm temperatures, and nutrients – and the bloom is still with us. What will reduce the problem will be wind and currents to drive it offshore… and time – the Gulf will eventually cool and the tide will be reduced. How long is anyone’s guess.


So why is it 70 degrees in December?

That is a question for another article…


You can track red tides in the panhandle by visiting http://myfwc.com/REDTIDESTATUS

It’s Happening … Red Tide

It’s Happening … Red Tide

 Many coastal Panhandlers woke up this week to the sight and smell of dead fish. Thousands of them washed ashore from Panama City to Pensacola. This mass die off included a variety of species including whiting, sheepshead, hake, cusk eels, and even lionfish; there were also reports of dead bass from the Dune Lakes in Walton and Okaloosa counties. What caused this mass die off of fish?


The suspect is red tide…


Most of us along the panhandle have heard of red tide but we may not know what it is or what causes it. Many attribute the red tide events to human impacts, stormwater runoff etc., but in fact they have been around for centuries. There are records suggesting that the European colonials experienced them and I have read one account that the Red Sea got its name from the frequency of these events there. So what is this “red tide” and what causes it?

Dead fish line the beaches of Panama City. Photo: Randy Robinson

Dead fish line the beaches of Panama City.
Photo: Randy Robinson


It is actually a bloom of small single celled plants called dinoflagellates. There are thousands of species of dinoflagellates in the world’s oceans and not all cause red tide, but there are several species that do. These small microscopic plants drift near the surface of the ocean acquiring sunlight to photosynthesize. They possess two small “hairs” called flagella (hence the name “dinoflagellate”) to help orient themselves in the water column. Most have a shell covering their body called a theca and some shells have small spines to increase their surface area to resist sinking. One method of defense found in some dinoflagellates is the production of light – bioluminescence. This light is produced by a chemical reaction triggered by the creature as a flash of blue – many locals refer to it as “phosphorus”. Other dinoflagellates instead will release a toxin… some of these are ones we call “red tide”.


Red tide organisms are always in the water column of marine environments but are usually in low concentrations, maybe 300-500 cells per milliliter of water. But under favorable conditions, warm water with nutrients, they multiple… sometimes in great numbers, such as 3000-5000 cells/ml, and we have a “bloom”. The number of cells within these blooms can be high enough that we can actually see the water change color… hence “red tide”.

The dinoflagellate Karenia brevis. Photo: Smithsonian Marine Station-Ft. Pierce FL

The dinoflagellate Karenia brevis.
Photo: Smithsonian Marine Station-Ft. Pierce FL


The most common red tide dinoflagellate associated with the Gulf of Mexico is Karenia brevis. Karenia blooms typically form offshore and are of little impact to the coastal communities. However when the wind and tides are right these blooms will drift towards shore. When they do fish kills occur and humans have eye and throat irritations. Marine mammals in particular struggle with red tide. As the bloom comes near shore it reaches the bottom of the water column and many of the bottom dwelling fish suffer. Most of the photos of fish I saw in the October 2015 fish kill were bottom dwellers, including many invasive lionfish.


Is there anything we can do to prevent red tides?


Not really… Again, they are naturally occurring event. We may increase the frequency of the events by discharging excessive nutrients into the water from our run-off but they would probably occur anyway. Red tide events are not as common in the panhandle as they are in southwest Florida. The Gulf waters near Charlotte Harbor are shallow, warm, and near the many manicured lawns, gold courses, and the discharge of much of the agriculture in the state. Occasionally blooms formed in that part of the state drift north but this year a bloom formed off of Bay and Gulf counties in early October. The recent storm that passed through probably pushed the bloom inland and to the west. The biggest hazard of humans is eye, throat, and skin irritation. It is quite uncomfortable to be around these blooms. In 1996 a local bloom was concentrated enough that the campground at Ft. Pickens had to be closed. I was in Galveston Texas when I heard about the red tide occurring in the Florida panhandle. As I was leaving Galveston the newspaper reported the closer of all oyster harvesting in Texas due to a red tide generated in the Padre Island area and was moving north. Seems that red tide is covering a large portion of the Gulf coast the last week of October. That said… anything communities can do to reduce nutrient runoff will certain decrease the frequency of red tides.

The carcass of the invasive lionfish was part of the October red tide kill. Photo: Shelly Marshall

The carcass of the invasive lionfish was part of the October red tide kill.
Photo: Shelly Marshall

The Florida Fish and Wildlife Conservation Commission post red tide updates from around the state on their website and the Escambia County Extension Office post a local water quality update each Friday that has red tide information as well.





Escambia County Extension