![]() ![]() Some of these blooms can be harmless, because not all produce the toxin domoic acid. The Pseudonitzchia species of algae, forms of diatoms, more commonly create red tides off the coast of California. At these much higher concentrations, the toxin poisons shellfish and if consumed, can lead to paralytic shellfish poisoning in people. Alexandrium produces the toxin saxitoxin, which remains in the gulf in low concentrations during the year and explodes during blooms.ĭuring a bloom, filter-feeders like clams inadvertently consume the toxin as they filter the water for food (algae), and the toxin accumulates inside their tissues. When the water temperature exceeds 50☏, generally in late spring, the cysts “perk up,” says Stumpf, and swim up to the surface to start growing. The result tends to only turn the characteristic red color when it blooms and concentrates in a front, the boundary between two pooling water sources.Īlexandrium has a fascinating life strategy, feeding, aggregating to reproduce, and then resting on the ocean floor as a dormant hard cyst over the winter. In the Gulf of Maine, Alexandrium catanella and Alexandrium fundyense are the main culprits for red tides. While a typical Florida bloom lasts from five to seven months, Cynthia Heil, director of the Red Tide Institute at Mote Marine Laboratory & Aquarium in Sarasota, said Ian’s 20-inches of rainfall has played a role in the current bloom, which is impacting areas along the entire coast. brevis with a food source of crucial elements: phosphorous, nitrogen, and iron.Īs of March 2023, Florida is in month five of a red tide bloom post-Hurricane Ian, which has been interfering with residents and spring breakers who chose the state’s Gulf coast as their getaway destination. The cyanobacteria consume nitrogen from the atmosphere and when they die, they provide K. In particular, a cyanobacterium, Trichodesmium, blooms in the Gulf of Mexico after iron-rich dust drifts over from Africa. brevis can interact with other types of algae, worsening the overall red tide. Unauthorized use is prohibited.Įven at relatively low levels, K. Louisiana and Alabama cases tend to appear more rarely, often only when hurricanes push blooms northwest from southwest Florida. In Texas, they used to bloom every ten years, but now appear every three years. Richard Stumpf, an algal blooms expert at the National Oceanic and Atmospheric Administration (NOAA), says red tides tend to occur in Florida every year. With their characteristic red color, these red tides affect Florida, Louisiana, Alabama, and Texas. These blooms release massive amounts of brevotoxin into the ocean. When environmental conditions, like temperature, nutrient levels, and wind, are right, the algae population explodes and huge blooms form. ![]() ( Read more about red tides in Australia.)Ī type of toxic algae, Karenia brevis, lives in the Gulf of Mexico throughout the year at low concentrations. In each of these locales, a different microorganism-present at low levels normally-generates the algal bloom when conditions align. Within the United States, red tides occur most commonly in the Gulf of Mexico, off California, and in the Gulf of Maine. ![]() The algae color ranges from rusty orange to green to bioluminescent, depending on the pigment of the cells and local atmospheric conditions. And despite the name, not all red tides are red. These microscopic forms of algae produce toxins that can sicken humans and be fatal for marine animals. What is a red tide?Īt least three species of dinoflagellates and one diatom species are responsible for the toxic mess of red tides in the United States. ![]()
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