Red tide made news when it forced people in Toledo, Ohio to stop using tap water last week due to a poisonous bloom in Lake Erie. The current toxic bloom off the Florida coast probably won’t cause as much of a problem to the every day lives of Floridians as it did to those in Ohio, but it is the largest red tide bloom the state has seen in nearly 10 years. As it approaches the coast, it has already managed to kill thousands of fish and other marine animals.
According to the Florida Fish and Wildlife Conservation Commission, the 80 mile long and 50 mile wide red tide bloom is made up of the microorganism Karenia brevis. It doesn’t pose a health risk to humans out at sea (It’s currently between 40 and 90 miles off the coast.), but may do so if it washes ashore. It’s a naturally occurring phenomenon which happens when a normal algae bloom gets out of control. In doing so, the toxins it produces become so prevalent that they can become deadly to marine life that happen to swim into it.
When a bloom gets out of control, the algae release an odorless chemical which stains the water a reddish or brownish color, and this is where the “red tide” gets its name. While it can be deadly to marine animals that wander into its path, it’s rarely deadly to humans. It can, however, cause minor respiratory distress in people. According to the Centers for Disease Control and Prevention (CDC) the greatest risk comes from humans eating shellfish contaminated with the toxins, but according to the CDC this rarely happens:
“In the US, one of the illnesses that may result from eating algae toxin-contaminated shellfish is neurotoxic shellfish poisoning (NSP). NSP is caused by eating shellfish contaminated with brevetoxins, which are produced by Karenia brevis, the marine algae associated with Florida red tides. NSP is a short-term illness with neurological symptoms (such as tingling fingers or toes) and gastrointestinal symptoms. There are very few cases of NSP in the US because coastal states carefully monitor their shellfish beds and close the beds to harvesting if high concentrations of brevetoxins are detected in the water or the shellfish.”
For those who will be in Florida waters over the next few weeks, be sure to watch for information about the red tide happening there to avoid any health risks that can come with it.
(Photo courtesy of the Florida Fish and Wildlife Conservation Commission)