RED TIDE Definition & Meaning

red tide

noun

a brownish-red discoloration of marine waters caused by the presence of enormous numbers of certain microscopic flagellates, especially the dinoflagellates, that often produce a potent neurotoxin that accumulates in the tissues of shellfish, making them poisonous when eaten by humans and other vertebrates.

red tide

noun

a discoloration of sea water caused by an explosive growth in phytoplankton density: sometimes toxic to fish life and, through accumulation in shellfish, to humans

red tide

A population explosion of certain species of dinoflagellates, a kind of protozoan found in plankton. The dinoflagellates color the water red or reddish-brown and secrete a toxin that kills fish. Red tide usually occurs in warm coastal waters.

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51�Թ� History and Origins

Origin of red tide¹

First recorded in 1900–05

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Example Sentences

Examples have not been reviewed.

A red tide washed through the neighborhood in recent months, and Trump drew more votes in Pico-Robertson than the previous two elections combined.

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There was a weak El Niño earlier this year, and this wash-up coincided with the recent red tide and Santa Ana winds last week.

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“I did notice that the ocean was really red-brown last week, but I didn’t put it together that the smell was linked to the red tide,” she said.

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During the day, those dinoflagellates cast a rusty hue across the ocean — often called a “red tide” — which sky cameras on Tuesday captured around the Santa Monica Pier.

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Sawfish necropsies have not revealed any pathogen or bacterial infections, nor problems with low water oxygen levels or contaminants such as chemicals, or toxic red tide.

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