- red tide
a brownish-red discoloration of marine waters caused by the presence of enormous numbers of certain microscopic flagellates, esp. 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.[1900-05]
* * *Discoloration of seawater caused by dinoflagellates during periodic blooms (population increases).Toxic substances released by these organisms into the water may be lethal to fish and other marine life, and they irritate the human respiratory system. Coastal resorts sometimes close when breaking waves release the toxic substances into the air. The causes of red tide are uncertain; it may require the confluence of several natural phenomena, in which human influence may or may not play a part.
* * *discoloration of sea water (water bloom) usually caused by dinoflagellates (dinoflagellate), during periodic blooms (or population increases). Toxic substances released by these organisms into the water may be lethal to fish and other marine life. Red tides occur worldwide in warm seas. Up to 50 million cells per litre (quart) of the species Gymnodinium brevis caused a red tide off the Florida coast in 1947 and turned the water from green to yellow to amber; thousands of fishes died. A red tide along the Northumberland coast in England in 1968 was the cause of the death of many sea birds. Similar red tides, caused by Gonyaulax polyedra, have occurred off the California and Portuguese coasts. Toxins released into the water are irritating to the human respiratory system; they may become public health problems at coastal resorts when breaking waves release the toxic substances into the air.
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