[citation needed] These explorers noted large fish kills that resemble the die offs seen in present-day due to K. brevis.

The swimming speed of K. brevis is about one metre per hour[13] and the organism can be found throughout the year in the waters of the Gulf of Mexico at concentrations of ≤ 1,000 cell per liter.

[14] Karenia brevis is the causative agent of red tide, which occurs when the organism multiplies to higher than normal concentrations.

During these events the water can take on a reddish or pinkish coloration, giving these explosions in the K. brevis population the name of Florida Red Tide.

Under favorable conditions, toxin-producing dinoflagellates such as K. brevis flourish and grow to high concentrations, an event termed a "harmful algal bloom" or a "HAB".

Due to the toxin that K. brevis produces, these red tides can be detrimental to marine life and can even affect human populations along coasts where they occur.

It is only at times of unchecked population growth, resulting in harmful algal blooms, when the organism is of concern to human health and activities.

Although no recorded human deaths have occurred from NSP, the poisoning does result in nausea, vomiting and a variety of neurological symptoms.

[15] The uncontrolled mass explosions of K. brevis populations resulting in Florida Red Tide also has a significant financial impact on the affected coastal areas.

During periods of red tides this important source of revenue is often lost to the impacted coastal communities of Florida, often on the scale of tens of millions of dollars.

Extended occurrences of red tide blooms in the Gulf of Mexico have been associated with substantial instances of mortality in manatee populations[25].

The "Brevebuster" is a deploy-able instrument that can be deployed on automated underwater vehicles or on stationary platforms that can optically detect the Florida red tides.

[6] A molecular, real-time PCR-based approach for sensitive and accurate detection of K. brevis cells in marine environments has therefore been developed.

[27] A real-time nucleic acid sequence-based amplification (NASBA) assay has been developed for detection of rbcL mRNA from K. brevis.

NASBA is sensitive, rapid and effective, and may be used as an additional or alternative method to detect and quantify K. brevis in the marine environment.

[32][33][34] In addition to methods of detection of cells of K. brevis, enzyme-linked immunosorbent assay (ELISA) and liquid chromatography mass spectrometry (LCMS) have been developed for detecting brevetoxin in shellfish,[6][35] are more sensitive than the standard mouse bioassay, and as of 2008, were being considered by the Interstate Shellfish Sanitation Conference for regulatory use.