Red tides are algal blooms that turn coastal waters red or brown. They are caused by large concentrations of certain microalgae that produce powerful toxins harmful to marine life and humans. Symptoms in humans can include diarrhea, paralysis, memory loss and difficulty breathing. Red tides have occurred for thousands of years but seem to be increasing in frequency, duration and geographical range due to pollution, rising sea temperatures and other environmental factors.

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What are Red Tides?

5. . Figure 1. Two examples of red tides a) Cape Rodney, New
Zealand b) a bloom of Noctiluca scintillans, La Jolla,
California.
What are Red Tides?
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