Bioluminescent Beaches – Kavaru

Context: Recently, bioluminescent blue waves were observed in the backwaters of Kochi, Kerala.

What is Bioluminescence or Kavaru?

• Bioluminescence is the emission of light by living organisms in the water caused by microscopic organisms:
  • Plankton (Noctiluca scintillans or sea sparkle)
  • Certain algae, fungi and bacteria
• These organisms produce light through a chemical reaction inside their bodies.
• The reaction involves a light-emitting pigment (luciferin) and an enzyme (luciferase).
• When water is disturbed — by waves, movement of boats or even footsteps — the organisms light up as a defence mechanism or to attract mates.
• The glow is usually blue, but sometimes red or brown (called red tide) depending on species and concentration.
• It got popularised in the public imagination through the Malayalam film “Kumbalangi Nights“.

• Bioluminescence can occur in: Beaches and shallow waters, Backwaters and estuaries & Paddy fields near coasts (like Kerala’s pokkali fields)

What Causes These Blooms?

• Environmental Factors: Eutrophication, High salinity and turbidity in estuarine and coastal waters, rising temperatures and reduced rainfall.
• Human-Induced Drivers: Agricultural runoff, urban discharge and Industrial effluents from nearby regions.

Famous Indian Spots

• Kumbalangi & Chellanam (Kochi, Kerala)
• Thiruvanmiyur Beach (Chennai)
• Betalbatim Beach (Goa)
• Bangaram Island (Lakshadweep)

Ecological Implications

On Marine Ecosystems

• Algal blooms can lead to Harmful Algal Blooms (HABs) causing hypoxia (low oxygen) → fish deaths, and biodiversity loss.
• It releases toxic compounds like: Hepatotoxins, Neurotoxins, Dermatotoxins etc.

On Aquatic Food Chains

• While plankton are crucial in the marine food chain, in excess they release harmful substances:
• Dimethyl sulfide, dissolved organic carbon, ammonium etc.

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