Scientists for the first time have observed and scientifically documented a rare and visually magnificent phenomenon known as coral spawning in Lakshadweep signalling good health of corals on the west coast.

Popularly known as “sex-on-the-reef”, coral spawning is sexual reproduction of corals, which involves mass collective expulsion of colourful eggs and sperm clouds into the water by corals. Normally taking place once a year close to a full moon night, the gametes then rise to the surface of the ocean creating a colourful slick, which can be seen clearly from the sky.

The slick was first observed by Wildlife Trust of India (WTI) marine biologist S Subburaman last week and a team from the Central Marine Fisheries and Research Institute (CMFRI), Kochi. Subsequent laboratory analysis confirmed them as coral spawn.

“It is now being seen over a large area. I have seen it in three islands and getting reports that spawn is now being seen around other islands,” Abdul Raheem, an environmental warden from Lakshadweep forest department told Deccan Herald on Tuesday.

Post-confirmation survey showed the larvae were seen forming slick-like layers around four islands – Agatti Island, Bangaram, Thinakara, and Kavarrati, according to a press statement issued by the WTI.

“This proves Lakshadweep’s corals are recovering from the stress they experienced after El Niño, 2010,” Raheem said.

During spawning, eggs are fertilised and form larvae. The larvae then float off for one-two months till they find suitable substrates, settle and form their own colonies, helping corals thrive. It was first recorded in 1981.

Coral spawning is a big tourist attraction in the Great Barrier Reef in Australia, where it generally happens soon after the full moon in November or December. In the Maldives, spawning has been scientifically determined to take place between the end of January and the beginning of March.

One thing is universal though – exact date of spawning is still largely unpredictable.

The Lakshadweep spawning was observed little earlier than expected.

“We expect corals to spawn a week after full moon nights in March (27th for this year) or April (25th for this year). This event shows that corals spawn in day as well, though not as common as at night,” said Alasdair Edwards, professor at Newcastle University, UK.

Since the health of corals depended a lot on sea temperature, the corals might suffer yet another round of bleaching if the temperature goes up more than usual, warned Raheem.
But for the moment, it was an wonderful sight for scientists and environmentalists at Lakshadweep who were witnessing it, said BC Choudhury, senior advisor of WTI.