he text for this essay is found in the second book of the Holy Bible, Exodus 7:20-21, “And all the waters that were in the river were turned ·into blood, and the fish that were in the river died; and the river stank. And all the Egyptians digged round about the river for water to drink; for they could not drink of the water of the river." It seems appropriate to begin a dissertation on the Red Tide with what I take to be the earliest recorded reference and, being in the Bible, unquestionably authentic. What is the Red Tide? It is a discoloration of costal sea water -- sometimes extending into rivers -- caused by enormous numbers of tiny unicellular organisms belonging to the order of dinoflagellates. Al dinoflagellates responsible for red tides and fish kills produce toxins, chiefly neurotoxins. These vary greatly in potency or degree of toxicity. Gonyaulax catenella, the variety that blooms on the north Pacific coast produces a toxin said to be 100,000 times more potent than cocaine. G. breve is considerably less toxic. The killing effect is largely confined to vertebrate fish, that is, fish with a well-developed central and peripheral nervous system. What is said of fish does not apply to filter-feeding bivalves, namely, mussels, clams, and oysters. Exposed to dinoflagellates these mollusks accumulate and store toxin and, when eaten by humans, can cause illness and sometimes death.
Language: en
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