Sea sparkle sets Napier harbour alight

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

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 Napier's inner harbour.

Liv Jack, who runs the Whale Watch Hawke's Bay Facebook page, described the organisms as looking like tiny raindrops.

"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 page telling her about it, so she and her partner went down to the wharf to have a look.

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

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

"We had another report of it last year."

She said the organisms glowed as a defence mechanism.

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

That could come from waves, or hitting rocks. Scientists believed it was used to startle predators.

Madarasz-Smith said it was a natural phenomena.

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

Jack said people should get down and see them.