About

• Kochi’s backwaters, particularly around Kumbalangi, have become renowned for the captivating phenomenon of bioluminescence, locally known as ‘kavaru’. 
• This natural event is primarily observed between March and May, when certain microorganisms emit a radiant blue glow upon disturbance, creating a mesmerizing spectacle in the water.
• It is essentially a conversion of chemical energy into light caused by mechanical disturbances and shear stress acting on the organisms. One of the primary organisms responsible is Noctiluca scintillans, a microscopic plankton. 
• The glow is usually blue, but can also appear red or brown depending on the species involved
• When concentrations exceed half a million per litre, the phenomenon is known as a red tide.

Issues

• Plankton — mostly larval forms of marine species like prawns and mussels — are vital to aquatic food chains. 
• However, in large numbers, they release substances like dimethyl sulphide, dissolved organic carbon and ammonium, leading to the deterioration of water quality through Harmful Algal Blooms (HAB). 
• These can cause widespread marine mortality and loss of biodiversity. A common effect of HABs is hypoxia (low oxygen levels), which damages both natural ecosystems and fish farming operations.

• Furthermore, the quality and safety of fish for consumption is compromised when biotoxins accumulate, leading to reduced demand in local and export markets.

Measures taken

• The UNESCO Intergovernmental Oceanographic Commission’s Harmful Algal Bloom (IOC-HAB) Programme was established to support the understanding, monitoring, and management of harmful algal blooms.
• India has launched the INCOIS Algal Bloom Information System—an automated, web-based platform that utilizes satellite remote sensing data, in situ observations, and ocean models to detect, map, and forecast algal bloom occurrences.
• Key measures to alleviate toxic blooms include regulating coastal runoff, managing agricultural and urban waste and promoting sustainable aquaculture practices such as feed regulation. 
• Mangroves and seagrasses, which act as natural nutrient filters, are being restored in areas where they have declined.
• Public engagement through citizen science — including workshops, popular articles and local committee meetings — ensures community awareness and encourages effective long-term control strategies.