BLUE TIDES

Subject: Environment

Context : The tide that produces a fluorescent blue hue—bioluminescence, made an appearance on Tuesday night on Juhu beach in Mumbai and Devgad beach in Sindhudurg along Maharashtra’s coastline.

Concept:

• The natural phenomenon is characterised by the emission of light produced by phytoplanktons (microscopic marine plants), commonly known as dinoflagellates.
• The light is produced through a series of chemical reactions due to luciferase (oxidative enzymes) protein.
• Marine scientists said one of the main factors for its occurrence could be eutrophication – the reduction of oxygen in the water – which makes the phytoplanktons very dominant.
• This is a recurring phenomenon which is caused by a bioluminescent plankton called Noctiluca scintillans, commonly known as sea sparkle.
• While smaller blooms may be harmless, slow moving larger blooms may cause severe hypoxic conditions that result in fish die-offs in an area.
• Similar to the blue tide, there exists another such phenomenon called red tide or harmful algal blooms that emits red light.
• It is rare occurrence caused when colonies of algae—simple plants that live in the sea and freshwater—grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds.