Red tide

Red tide, natural phenomenon caused by a sudden increase of microscopic reddish organisms on the surface of a body of water. Under optimum conditions, one celled organisms called dinoflagellates multiply by the millions and float on rivers, lakes, oceans, and arms of the oceans. Most red tides are harmless, but some types kill large fish and marine life by poisoning the water or using up the available oxygen supply. Why the dinoflagellate population suddenly proliferates is not completely understood, but scientists theorize that a combination of factors such as temperature, amount of sunlight, water currents, and availability of nutrients create ideal conditions for spawning. Some sea creatures feed off large numbers of the dinoflagellate colonies or eat the food the colonies thrive on, thus decreasing or ending the red tide.