UPSC CSE Prelims 1998
The phenomenon described refers to red tides. These are dense accumulations or blooms of certain species of pigmented dinoflagellates, which are microscopic phytoplankton. They occur in estuaries and coastal waters when environmental conditions, such as nutrient availability and water temperature, are favourable. The characteristic reddish or brownish discolouration of the water is due to the high concentration of photosynthetic pigments within these dinoflagellates. Although termed "tides," this refers to the extensive discolouration and apparent movement of the water mass, not the astronomical tidal movements. Some red tide species produce potent toxins that can be detrimental to marine organisms and human health, leading to events like paralytic shellfish poisoning.
Sea tides denote the periodic rise and fall of sea levels, primarily influenced by the gravitational forces exerted by the Moon and the Sun on Earth's oceans.
Black tides are typically associated with environmental disasters involving large-scale oil spills, which cause extensive dark discolouration of water and coastlines, rather than biological blooms.
Sea flowers is not a recognized scientific or ecological term for marine phenomena. It serves as a distractor option.