Expert Answers
amy-lepore eNotes educator| Certified Educator

According to enotes red tide is a condition where the sea appears to be a reddish-brown color.  

"This rusty-red discoloration is caused by an exploding population of tiny single-celled microorganisms called dinoflagellates, which are usually found in ocean water, but occasionally in lakes and rivers as well."

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atyourservice | Student

Red tides are caused by an explosive growth and accumulation of certain microscopic algae, predominantly dinoflagellates, in coastal waters.

ronald75 | Student

Red tide is actaullly a result of algal bloom..Also anthropogenic factors like pollution and natural factors cause red tides!