KOCHI: The natural bioluminescent phenomenon known locally as ‘kavaru’ is back in the backwaters of Kochi, especially along Chellanam, Kumbalangi, Edakochi, Perumpadappu, Kumbalam, Panangad, and Cheppanam. However, according to residents in these areas, this year has seen a late occurrence. But, with the sighting gaining more and more attention with social media reels and visitors arriving in droves, Kumbalangi panchayat has decided to market it.
According to M P Sivadathan, director of the Kerala Homestay and Tourism Society (K-HATS), visitors from all over Kerala come to see the phenomenon. “The other day, Kumbalangi panchayat held a meeting to draw up plans to make use of the phenomenon to draw more tourists. It has been decided to organise festivals or events in the areas where kavaru is visible. Also, help has been sought from law enforcement agencies to maintain law and order, besides ensuring the safety of visitors,” he added.
The phenomenon lasts for around two months, said V T Sebastian, convenor of the community collective Chellanam Aikya Vedi. “Usually kavaru appears towards the end of January. The delay is being linked to the climate, with lower atmospheric temperature believed to have led to low salinity in the backwaters,” he said. According to Sivadathan, this is not a recent development.
“The phenomenon has a long history here. In the past, it used to have a silver sheen. But over the years, in the last two to three years, to be exact, the colour has changed to blue. This is being attributed to the presence of a species of bacteria that glows blue,” said Sivadathan.
Attributing the fame to social media, he added that the phenomenon is, however, very fickle. “People arrive after viewing reels. However, the bioluminescence depends on a variety of factors, the important one being a high concentration of salt.
After heavy rain, with the dilution of the salinity, the kavaru also disappears. So, many times those arriving to see it have had to leave disappointed,” he added. “The bioluminescence is expected to be clearly visible by next month,” said Sebastian.
Some varieties of microorganisms, such as algae, bacteria, and fungi, have the ability to absorb sunlight in saline water and release it when agitated. The scientific world calls this bioluminescence.
“This blue light in the backwaters becomes visible to the naked eye only during summer when the salt content increases in the backwaters, similar to that of seawater. This is when the salt content is 25-35 PPT (parts per thousand) -- representing 25-35g of salt per 1,000g of water.
This can be seen well in the low-flow areas of the backwaters from February to April and May, when the summer is intense and there is an increase in the salt content,” he added. Kavaru first received attention with the release of the film Kumbalangi Nights.