Definitions for "Red tide"
A proliferation of a marine plankton toxic and often fatal to fish, perhaps stimulated by the addition of nutrients. A tide can be red, green, or brown, depending on the coloration of the plankton.
The term applied to toxic algal blooms caused by several genera of dinoflagellates (Gymnodinium and Gonyaulax) which turn the sea red and are frequently associated with a deterioration in water quality. The color occurs as a result of the reaction of a red pigment, peridinin, to light during photosynthesis. These toxic algal blooms pose a serious threat to marine life and are potentially harmful to humans. The term has no connection with astronomic tides. However, its association with the word "tide" is from popular observations of its movements with tidal currents in estuarine waters.
A phenomena that occurs near the surface of the sea and is caused by an abnormal growth of dinoflagellates, single-celled plankton. The toxin secreted by the dinoflagellates is capable of killing fish through a cyclic effect. As decomposition continues, it creates more nutrients, which feed the plankton bloom, and the greater quantities can color the water red.