Chennai sea's blue glow seen as bad for fish: Study

Analysis of samples has established that a blue glow witnessed recently in and around the city's coastline was due to blooming of sea sparkle species, a National Centre for Coastal Research scientist said on Sunday.

After a blue glow, known as bioluminescence was witnessed here, samples were collected by the NCCR to establish various parameters and scientifically confirm the species behind it.

"We have confirmed that it is Noctiluca scintillans (sea sparkle) of dinoflagellate (unicellular organism)," an NCCR scientist told PTI.

The species grew in size in a matter of few days and were also seen in places including Akkarai, Tiruvanmiyur and Elliot's beaches, he said.

Tamil Nadu Dr J Jayalalitha Fisheries University Vice-Chancellor S Felix had on August 20 said the blue glow may be due to the blooming of "non-toxic marine dinoflagellate species, called Noctiluca scintillans."

Generally, the formation of this bloom is considered a bad sign for the decline of fisheries in the particular location, Felix had said.

"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," he had remarked.

Since the night of August 18, 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," according to the varsity head.

The bioluminescent light emitted by this organism in the seawater 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 (the 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 a multiplication of this species, he said.

This species is known to feed on organisms including minute phytoplankton (consisting of microscopic plants), fish eggs and microzooplankton (tiny organisms, which are protozoans and animals).

Both phytoplankton and zooplankton are tiny organisms that float over the sea and freshwater bodies and play a key role in the marine ecosystem.