is the red tide harmful to humans?

Answer 1

No, it is produced by a red pigment from a type of protozoa called a dinoflagellate. Some dinoflagellates produce neurotoxins that are harmful, but not this one.

No deaths of humans have been attributed to red tide, but people may experience respiratory irritation (coughing, sneezing, and tearing) when the red tide organism (Karenia brevis) is present along a coast and winds blow its toxic aerosol onshore. Swimming is usually safe, but skin irritation and burning is possible in areas of high concentration of red tide. Source: University of Florida Marine and Natural Resources, IFAS Extension(http://taylor.ifas.ufl.edu/marine_redtide.shtml

Answer 2

It depends on which species of marine dinoflagellate (a type of phytoplankton) is causing the bloom (the red tide), but yes, most kinds of red tide are harmful to humans in some way.

The worst of these is Paralytic shellfish poisoning (PSP), caused by the Alexandrium species group, like those found in the Gulf of Maine and northern waters. These plankton have a toxin called saxitoxin, which stops nerve signals from reaching their destination. Symptoms of PSP include tingling in the extremities, which can travel to the chest cavity and stop your breathing. Severe cases can cause death, but usually a few weeks in the hospital on a respirator to control breathing will be all thats needed for a full recovery.

Another type of red tide causes Neurotoxic Shellfish Poisoning, which affects the same channels as PSP but acts differently by keeping nerve channels continously open, which can prevent your brain from working properly, but is NOT lethal. NSP is often associated with the red tides in Florida.

Amnesiac Shellfish Poisoning will cause you to have neurological and memory problems for a month or two. These are usually caused by a neurotoxin called domoic acid which increases the calcium ions in the nervous system which interrupts signals, but is also not lethal.

Diarrhetic Shellfish Posioning is never fatal, and usually involves 3-7 days with severe diarrhea and vomiting, because the body avoids absorbing the toxins by also not absorbing water during this period.

Red tide is usually transmitted to humans through the shellfish we eat. This is because shellfish are filter feeders, filtering thousands of gallons of seawater a day, so the toxins from the phytoplankton they are eating can build up in their tissues very quickly. The shellfish cannot digest or break down these toxins, they have to just wait out the bloom of plankton and once it is gone the toxin flushes out of their system.

Always know where your shellfish came from, or buy it from a grocery store or reputable fisherman who you know follows local regulations. Sometimes only a certain area of the coastline will be closed to shellfish harvesting, other times a whole state's coast will be closed. Find the website for your state Department of Marine Resources, and check to see if there are closures in your area.

Answer 3

YES! Red tides are a natural occurring bloom in the salt waters of the world, they are very toxic. They kill fish and other forms of marine life and can be deadly to humans. Stay clear of the areas in which they are found and do not eat any marine products from theses areas!!