Estuaries possess distinct blooms of excessive growth of a pigmented dinoflagellates. These blooms are called

The rapid, excessive growth of pigmented dinoflagellates in estuaries is commonly referred to as a “red tide,” a form of harmful algal bloom. Dinoflagellates and diatoms produce most harmful blooms in salt and brackish waters, including estuaries, and these blooms often discolor the water because of algal pigments and can generate toxins and oxygen depletion that harm marine life [3]. The name “red tide” is a widely used common name (historically based on the red or brown discoloration), although blooms can be other colors and are not caused by tides, so the term is somewhat of a misnomer [1]. Thus, “red tides” is the correct option.

Sources

1. [2] https://www.cdc.gov/harmful-algal-blooms/about/types-of-harmful-algal-blooms.html
2. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > Red Tide. > p. 27
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 26: Tropical Cyclones > Break Up Red Tide > p. 376