Blue glow on Chennai beaches: Phenomenon may be caused by sea sparkle

Chennai: An eerie blue glow in and around the city’s coastline has ignited a buzz among denizens and netizens but the phenomenon may be nothing more than the blooming of a non-toxic marine species, commonly called sea sparkle.

A scientist at the National Centre for Coastal Research here said samples were being analysed to ascertain factors like presence or absence of toxicity, the species, and the trigger for its blooming. “The samples are being studied and analytical results are expected,” Pravakar Mishra of NCCR said.

Asked about the phenomenon, also known as bioluminescence, Tamil Nadu Dr J Jayalalitha Fisheries University Vice Chancellor S Felix said it may be due to the blooming of “non-toxic marine dinoflagellate (unicellular organism) species, called Noctiluca scintillans (sea sparkle).”

Since Sunday night, a blue glow was witnessed in a couple of beaches – Tiruvanmiyur and Elliot’s in and around the city – which also led to animated discussions over the social media. The species, in view of its phosphorescent glow during night hours, is commonly called sea sparkle, the varsity head told PTI.

The bioluminescent light emitted by this organism in the sea water will be blue during night and during day, the water will look greenish. It is slimy in nature during heavy bloom since it contained “endosymbiotic (organism that lives in the cells of another organism) green algae species Pedinomonas sp.”

The blooming of bioluminescent marine algae generally appears after rainfall along the coast, which might bring in lot of nutrients and organic loadings and this could favour a sudden outburst in multiplication of this species, he said.

This species is known to feed on organisms including minute phytoplankton (consisting of microscopic plants), fish eggs and micro zooplankton (tiny organisms, which are protozoans and animals). Both phytoplankton and zooplankton are tiny organisms that float over sea and fresh waterbodies and play a key role in marine ecosystem.

“Sometimes, the liberation of ammonia from the cells of the noctiluca may cause the large-scale mass kill of fish during the crash of the bloom. …generally, the formation of this bloom is considered a bad sign for decline of fisheries in the particular location,” Felix said.