A rapid, dense proliferation of certain marine microalgae that can discolor coastal water reddish-brown and release potent toxins harmful to fish, marine mammals, birds and, through contaminated shellfish, humans. Blooms are triggered by a combination of warm water, abundant nutrients, often from agricultural or urban runoff, and calm conditions that let the algae accumulate near the surface, and can cause mass fish kills and force the closure of shellfish beds.
Facts
PeriodicityRecurs nearly every summer along Florida's Gulf Coast. 1 ScaleIndividual blooms can cover thousands of square miles, as with a 2015 bloom off China that covered about 13,500 square miles. 2 First DescribedFirst witnessed in the Gulf of Mexico region in the early 1500s by the Spanish explorer Cabeza de Vaca. 2 Identification
Distinguishing AppearanceThe bloom of algae often turns the water red. 1 Connections
Associated With
Red tide is the common name for a harmful algal bloom, typically one dominated by pigmented dinoflagellates or other algae that discolor coastal water; the two terms describe the same event.
Certain red tide events release biotoxins, such as domoic acid or brevetoxin, that are a documented direct cause of mass strandings of marine mammals and seabirds that ingest contaminated prey.
Sources
1. What is a red tide? - NOAA's National Ocean Service
paragraph 2, sentence on Florida Gulf Coast frequency
One of the best known HABs in the nation occurs nearly every summer along Florida's Gulf Coast.
paragraph 2, sentence on water color
As the name suggests, the bloom of algae often turns the water red.
View the Source2. Red tide - Wikipedia
Harmful effects, Economic impact, Recreation and tourism subsection
blanketed an even greater 13,500 square miles
Causes, Other causes subsection
HABs in the Gulf of Mexico were witnessed in the early 1500s by explorer Cabeza de Vaca.
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