The sight of hundreds of dead fish washing ashore on local beaches over the last five months is more than enough to make even an iron stomach turn. But is the same thing that’s killing marine life a cause for concern at your favorite seafood spot?
Dr. Razieh Farzad is a UF/IFAS assistant professor of food science and human nutrition and Florida Sea Grant affiliate researcher.
She says that the state of Florida highly regulates its commercial seafood to ensure no fish or shellfish have been harvested in areas impacted by red tide or contain the neurotoxin k. brevis. But if you’re fishing for fun, it’s wise to pay attention to local water quality advisories.
“Let me put it this way, if anyone does illegal harvesting, and they consume their seafood without paying attention to those advisories, that is coming out from our federal agencies and state agencies, then that can cause, potentially, some food safety problem or red tide-related food toxicity," said Dr. Farzad.
In extreme cases, humans poisoned by red tide’s neurotoxin can experience dizziness, respiratory issues, nausea, vomiting and disorientation. Dr. Farzad explains that mollusks and shellfish like clams, oysters and mussels, are the primary concern during a red tide event due to their filter-feeding abilities.
“They are cleaning the waters but at the same time during red tide, they can accumulate in this toxin up to 100 times more than what is the actual concentration in the surrounding water," said Dr. Farzad. "So, if we consume these shellfish, then that can lead to neurotoxin shellfish poisoning. It can get really dangerous.”
Since red tide is tasteless, Dr. Farzad says knowing the source of seafood is the best protection.
Learn more about red tide from environmental reporter Tom Bayles
What is red tide?
Red tide is one type of harmful algal bloom caused by high concentrations of the toxic dinoflagellate K. brevis, which is a type of microscopic algae found in the Gulf of Mexico. Red tide typically forms naturally offshore, commonly in late summer or early fall, and is carried into coastal waters by winds and currents. Once inshore, these opportunistic organisms can use nearshore nutrient sources to fuel their growth. Blooms typically last into winter or spring, but in some cases, can endure for more than one year.
Is red tide harmful?
K. brevis produces potent neurotoxins (brevetoxins) that can be harmful to the health of both wildlife and people. Wind and wave action can break open K. brevis cells and release toxins into the air. This is why you should monitor conditions and stay away from beaches where red tide is in bloom. People in coastal areas can experience varying degrees of eye, nose and throat irritation during a red tide bloom. Some individuals with chronic respiratory conditions like asthma or chronic lung disease might experience more severe symptoms. Red tide toxins can also affect the central nervous system of fish and other marine life, which can lead to fish kills.
What causes red tide?
A red tide bloom develops naturally, but recent studies have discovered mankind's infusion of other nutrients into the mix can make the red tide last longer or get stronger. But biology (the organisms), chemistry (natural or man-made nutrients for growth) and physics (concentrating and transport mechanisms) interact to produce the algal bloom. No one factor causes the development of a red tide bloom.
Environmental reporting for WGCU is funded in part by VoLo Foundation, a non-profit with a mission to accelerate change and global impact by supporting science-based climate solutions, enhancing education, and improving health.
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