"Red tides" called the rapid proliferation of dinoflagellates, coloring the water in rusty-red, sometimes observed in the vast waters. Red "bloom" of water is known from ancient times. This phenomenon Homer and Tacitus wrote, Cook and Darwin. A systematic study of the "red tide" began more than 100 years ago, and yet there is still no consensus on the reasons causing the mass reproduction of dinoflagellates. Difficulties in studying the "red tide" from acts of their occurrence, and the difficulty of predicting a relatively short period of existence. Interesting phenomenon in itself has great practical value associated with the deaths of large numbers of fish and other organisms caught in the "flowering" of water. No less significantly, and other circumstances caused by the fact that many mollusks (especially bivalves) become toxic during the "red tide." Only in the 30s showed that the toxicity of "red tide" is associated with dinoflagellates belonging to the genera GonVaulax, GVmnodinium, Peridinium, etc.
For the biology of dinoflagellates, as well as other protozoa, characterized by the formation of resting stages — cysts. These cysts on the continental shelf there may be up to several thousand per gram of sand. At some unpredictable time of tiny cysts of dinoflagellates, a new generation, which can also be the cause of the "red tide."
It should be emphasized that more "bloom" of sea water is at a relatively low titer of dinoflagellates in the daytime may not be detected. However, the night as a result of the luminescence inherent in these organisms, their clusters are clearly visible in the form of lights, flashing on the crests of waves. Night glow was long known natives of North America as a warning about the toxicity of shellfish-eating plankton. Typically "bloom" dinoflagellates covers the period from late spring to autumn. It was at this time the most frequent cases of shellfish poisoning. For many countries, where the clams are the traditional diet, this issue is of great epidemiological significance. Thus, the observed mass poisoning outbreak in Japan, Indonesia (island of Borneo), Spain, Italy, France, Germany, Sweden, USA and Canada.
Attempts to isolate and identify paralytic shellfish poison failed only in the late 50's, when Shantts et al (1957) Clam Saxidomus giganteus and Mytilus colifornianus identified toxin called saksitok-Sin. Subsequently saxitoxin was obtained from dinoflagellates GonVaulax catenella and thus proved the causal link between toxic shellfish and "red tide."