Napier inner harbour treated to natural light show

Noctiluca scintillans glow to warn away predators, giving off a spectacular light show. Photo / File

It was a light show to rival Guy Fawkes Day, but rather than a pyrotechnician shooting fire in the sky, it was a single-celled organism sparkling in the water.

Ahuriri was treated to a display of bioluminescent organisms called Noctiluca scintillans, or sea sparkle, which was spotted on Wednesday night in the inner harbour.

Liv Jack, who runs the Whale Watch Napier Facebook page, described the organisms as looking like tiny rain drops.

"Like when rain bounces off a puddle and there's the little, tiny droplets that come off it, it looked like that but glowing in the water."

She said someone had messaged the Whale Watch page telling her about it, so she and her partner went down to the wharf to have a look.

"My partner actually walked down on to some of the smaller stones and straight away it lit up under his feet, like glowing shoes."

Hawke's Bay Regional Council's principal scientist marine and coast, Anna Madarasz-Smith, said it was not uncommon at this time of year.

"We had another report of it last year."

She said the organisms glow as a defence mechanism.

"It's a chemical reaction that occurs when they're agitated."

This agitation could come from waves, or hitting rocks, and scientists believe it is used to startle predators.

"They'll emit light and that might startle the predator."

Madarasz-Smith said it was a very natural phenomena.

"It's just a normal, natural cycle they go through."

Jack said people should get down and see them.

"If you get the chance to see it, do it."

The sea sparkle was seen in Ahuriri, in the inner harbour.