red tide

noun

Definition of red tide

: 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 Early in the pandemic, the county’s beaches were shut down to prevent the spread of the virus, only to reopen in late April as the ocean coughed up a surprise with an algae bloom known as a red tide. San Diego Union-Tribune, "North County: A Year in Review," 27 Dec. 2020 This time of year, coho salmon are coming in from the ocean to head upstream to spawn—and potentially passing through the red tide. National Geographic, "Massive marine die-off in Russia could threaten endangered sea otters, other vulnerable species," 16 Oct. 2020 Stone crab hauls have faced many challenges over the years: Hurricane Irma, red tide and blue-green algae blooms took their toll. Chris Perkins, sun-sentinel.com, "Stone crab season is under way with a mix of optimism and uncertainty under a coronavirus cloud," 16 Oct. 2020 Senate District 28, which includes all of Evangeline Parish, is emblematic of the rising red tide in Louisiana. Tyler Bridges, NOLA.com, "This parish once elected Democrats. Now, it exemplifies why Trump is likely to win big in Louisiana.," 3 Oct. 2020 Phytoplankton cells that cause a red tide contain pigments for capturing the sunlight needed for cell nourishment, growth, and reproduction. David L. Coddon, San Diego Union-Tribune, "Arts & Culture Newsletter: Go behind the scenes with Elton John at the Troubadour," 3 Sep. 2020 That funding would help enhance regional water storage capacity, and reduce polluted discharges from Lake Okeechobee, helping address the problems of blue-green algae and the red tide. Abby Smith, Washington Examiner, "Daily on Energy: Trump bets that all environmental politics is local," 8 Sep. 2020 Bioluminescence expert Michael Latz from Scripps Institution of Oceanography discusses the most recent red tide event and explains why scientists still have many questions about this natural phenomenon. David L. Coddon, San Diego Union-Tribune, "Arts & Culture Newsletter: Go behind the scenes with Elton John at the Troubadour," 3 Sep. 2020 This year, a group of local photographers decided to take the gamble after noting a spate of red tide off Newport Beach, which, as of April 28, is still open to the public. Katherine J. Wu, Smithsonian Magazine, "Dolphins, Surfers and Waves Sparkle in Bright Blue Bioluminescent Glow Off California Coast," 28 Apr. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'red tide.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of red tide

1904, in the meaning defined above

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The first known use of red tide was in 1904

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Last Updated

8 Jan 2021

Cite this Entry

“Red tide.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/red%20tide. Accessed 16 Jan. 2021.

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More Definitions for red tide

red tide

noun

Medical Definition of red tide

: 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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