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red tide
noun
: seawater discolored by the presence of large numbers of dinoflagellates (as of the genera Karenia, Gymnodinium, and Alexandrium) which typically produce a toxin poisonous especially to many forms of marine vertebrate life and to humans who consume contaminated shellfish compare saxitoxin
Examples of red tide in a Sentence
Recent Examples on the Web
The organism that causes red tide is toxic and can affect the central nervous system of fish, often killing them.
—Kinsey Crowley, USA TODAY, 7 Mar. 2024
Resilient red tide Over the last decade, Tiernan says there’s been a spate of massive crabling returns–markedly increasing the population.
—Lauren Leffer, Popular Science, 11 July 2024
Beyond the evacuations, the contaminated release triggered a toxic red tide outbreak that killed more than 600 tons of fish and other aquatic life in summer 2021 around the Tampa Bay area.
—Curt Anderson, Sun Sentinel, 9 July 2024
Florida’s state wildlife and environmental agencies have ruled out exposure to red tide, water temperature and salinity.
—Max Chesnes, Orlando Sentinel, 26 June 2024
See all Example Sentences for red tide
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'red tide.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Word History
First Known Use
1904, in the meaning defined above
Dictionary Entries Near red tide
Cite this Entry
“Red tide.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/red%20tide. Accessed 5 Oct. 2024.
Kids Definition
red tide
noun
: seawater discolored and made poisonous by the presence of large numbers of dinoflagellates
Medical Definition
red tide
noun
: a large area of seawater discolored by the presence of large numbers of dinoflagellates (as of the genera Karenia, Gymnodinium, and Alexandrium) which typically produce toxins poisonous especially to many forms of vertebrate marine life and to humans who consume contaminated shellfish
In simple terms, a red tide is a dinoflagellate population explosion, caused when certain species "bloom," or multiply many times faster than usual.—Ellen Girardeau
Red tides, the blooms of toxic Karenia brevis algae that appear almost every year in Florida, often lasting for months and turning the ocean red, may be dangerous to asthma sufferers—even if they don't go swimming.—Nicholas Bakalar
see brevetoxin, saxitoxin, shellfish poisoning
More from Merriam-Webster on red tide
Britannica.com: Encyclopedia article about red tide
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