Sydneysiders who opted for a late-night stroll by the ocean would have been treated to a romantic sight on Sunday night as the ocean literally glowed blue with each rolling wave.
As delighted Manly Beach locals… shared snaps of the strange phenomenon across social media, Iain Suthers from the University of New South Wales told Daily Mail Australia that the strange glow is likely to continue over the next few days before dispersing over the weekend.
The oceanography expert said the colourful display was nothing to be concerned about, describing it as ‘a seasonal event, welcoming the early stages of spring’.
‘The glow is caused by Noctiluca scintillans, which is a single celled phytoplankton – the algae of the sea – which blossoms in the spring and the autumn and in 90 per cent of occasions occurs due to natural causes,’ Mr Suthers said.
‘It has organs inside its cells which allow it to bioluminate. It is really common in the deep ocean and only occurs at night when the animals – like squid or fish, bacteria or single cell pytoplantuum – use it to communicate.
‘They might just have bacteria they have on their bodies, or they have their own enzymes to make themselves glow.’
Mr Suthers, who researched the environmental spectacle 10 years ago, said that the algae appears due to a certain sequence of events that occur in the ocean, but that the exact environmental recipe for its occurrence is still unknown.
‘They probably started up off the coast of Port Stephens, where the eastern Australian current separates from the coast,’ Mr Suthers said of Sunday night’s event.
The natural oceanographic up-welling of nutrients which occurs in this area, as well as the nutrients from the recent rainfall, followed by the stable calm conditions and plenty of sunlight, are likely to have brought the algae to the surface.
Mr Suthers explained that the bizarre carnivorous cell, which preys on another type of algae called diatoms, gives off the luminous glow as a defence mechanism.
‘It eats these diatoms and grows and blooms and divides and it fills the water column and they float to the surface as a whole when the population starts to age,’ he said.
‘These cells glow at night, at any stage of their life, from when they first start to divide.
‘What causes it is a little pressure from the breaking of wave or when you dive in to the water- any sense of pressure change like that, indicates that a predator is about to eat them.
‘And so they give off this beautiful bioluminescence signal to warn off any potential predators trying to have a go at them.’
Photo caption: The colour came from a group of single-celled phytoplankton at the waters surface, called Noctiluca scintillans. The cells glow when they senses a pressure change, which indicates that a predator is about to eat them