The frequency and intensity of harmful algal blooms (HAB) are escalating in seas and oceans globally due to climate change and other factors such as increased nutrient inputs (nitrogen and phosphorus) from human activities. HAB are primarily composed of dinoflagellates (single-celled organisms with two flagella) common in marine and estuarine environments. Many HAB contain natural toxins that cause a variety of poisonings in humans (e.g. diarrhetic shellfish poisoning, neurotoxic shellfish poisoning, paralytic shellfish poisoning, and ciguatera poisoning).
Interpretation of red tide based on photograph from National Institute of Water & Atmospheric Research, New Zealand with permission.
Karenia brevis (dinoflagellate in Gulf of Mexico, Atlantic Ocean shore, and Gulf Stream north to Delaware) causes neurotoxic shellfish poisoning (NSP) in humans who eat shellfish containing brevetoxins produced by the dinoflagellate. NSP can cause slurred speech, dizziness, nausea, parathesis of lips, mouth, and tongue, vomiting, ataxia, and in some, partial paralysis and respiratory distress. Brevitoxins are not destroyed by cooking or freezing shellfish.
Interpretation of harmful algal bloom based on Copernicus satellite image in Marmara Sea..
Pyrodinium bahamense (an equatorial dinoflagellate) causes paralytic shellfish poisoning (PSP) in humans who eat shellfish containing saxitoxins produced by this dinoflagellate. PSP causes nausea, vomiting, parathesias (tingling and pricking sensations), coordination loss, speech defects, and death. Saxitoxins are not destroyed by cooking or freezing shellfish.
Interpretation of harmful algal bloom in Barents Sea photograph by Envisat.
Gambierdiscus toxicus (an equatorial dinoflagellate) contain the toxin ciguatoxin which causes ciguatera poisoning in humans who eat fishes high on the food chain (barracuda, moray eel, grouper, amberjack, sea bass, sturgeon, parrot fish, surgeonfish, red snapper among others). Ciguatera poisoning presents as diarrhea, vomiting, dizziness, itchiness, numbness, weakness, and sensitivity to hot and cold. Ciguatoxin is not destroyed by cooking or freezing.
Dinophysis toxicus (distributed globally) and related dinoflagellates can cause diarrhetic shellfish poisoning (DSP) in humans who eat shellfish containing with okadaic acid produced by the dinoflagellate. DSP causes diarrhea (most common), nausea, vomiting, and abdominal pain. Okadaic toxin is not destroyed by cooking or freezing shellfish.
