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 Elsewhere, other threats continued, like collisions with boats and poisoning from red tide, a toxic algae. Jason Gulley Catrin Einhorn, New York Times, 7 Mar. 2024 There are tens of thousands of different species of phytoplankton that each have unique interactions with their environment: some beneficial and some potentially harmful, like toxic algal blooms called red tides. Justine Calma, The Verge, 8 Feb. 2024 While a red tide is an extreme example, different kinds of phytoplankton can make the surface of the sea appear to be different colors — albeit in ways that are often too subtle for the human eye to detect. Justine Calma, The Verge, 8 Feb. 2024 One red tide off of Florida in 2021 left 600 tons of dead fish on the Tampa Bay beaches. TIME, 5 Feb. 2024 Five current and former local government officials from across Florida told the Times fertilizer bans are helping their communities decrease pollution that can fuel harmful algal blooms like red tide or toxic blue-green sludge. Max Chesnes, Sun Sentinel, 11 Jan. 2024 Wolfe initially feared the color was a sign of a toxic algal bloom, such as the type that produces red tides, per the publication. Margaret Osborne, Smithsonian Magazine, 21 Dec. 2023 And then, as soon as the red tide had ebbed, the All Clear was sounded. Neal B. Freeman, National Review, 26 Jan. 2024 Another study cited land reclamation, along with brine and industrial waste, as a cause of the excessive growth of microscopic algae in the Persian Gulf, known as algae blooms or red tides. Arielle Paul, New York Times, 18 Nov. 2023

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

Time Traveler
The first known use of red tide was in 1904

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 15 Apr. 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

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