Karenia brevis

Karenia brevis, a marine dinoflagellate common in Gulf of Mexico waters and is most
prevalent along the southwest Florida shelf, is the organism responsible for Florida red tide. Karenia brevis requires light and because of this, it cannot exist below 200 meters from the surface. They also provide a great deal of oxygen, and it's estimated that Karenia brevis can produce about 20% of the oxygen near the gulf during a bloom.

Karenia brevis

The most common reason for an algal bloom is dumping from chemical run-off zones. The algal blooms can deplete the water's oxygen and shade for the sun, preventing organisms that require sunlight from obtaining the sunlight.

Red Tide

Red tides are harmful towards marine and human life. Neurotoxic shellfish poisoning (NSP) is caused by consumption of molluscan shellfish contaminated with brevetoxins primarily produced by the dinoflagellate, Karenia brevis. NSP causes a wide range of symptoms, both neurological and gastrointestinal. Most people report multiple symptoms that range from mild to moderate nausea to vomiting and diarrhea. However, the most frequent symptoms individuals describe are numbness and tingling in the lips, mouth and face, as well as numbness and tingling in the extremities. The numbness can range from minor to severe. Overall loss of coordination and partial limb paralysis also may occur. Similarly, slurred speech, pupil dilation, overall fatigue, and headaches are commonly reported. Also, the victims have been described as looking disoriented and intoxicated. A few individuals have had respiratory discomfort and distress and throat tightness and chest heaviness have also been reported.

Dead Fish from Red Tide


NSP has resulted in high fish marine mortality which harms the coastal economy as a result of depleted fish supply because fishing is one of the largest industries on the coast.



- Victoria Mehlhaff -