How tiny organisms light up seashores with glowing blue waves

Andrew Fazekas
Weather and Science writer
A couple sits on the sand of Sydney's Manly Beach as they watch blue bioluminescent waves. (Reuters)

This week as night fell on southern Tasmanian seashores they appeared to light up the waters with a bizarre glowing sea of blue stars.

While glowing, rolling waves around Hobart made it look like scenes straight out of the alien Avatar movie, the jaw-dropping phenomena is in fact a natural light show sparked by billions of tiny marine organisms.

Fluorescent plankton known as dinoflagellates are sea creatures that are barely visible to the naked eye and are commonly referred to as algae. Whip-like projections called flagella allow them to swim fast while internally they produce their own form of bioluminescence. And when they occur in great numbers, they can form intense and spectacular phosphorescent blooms around beach areas as they become agitated by the turbulent surf.

They can become extremely common, up to a million critters per milliliter during blooms like you have with the fabulous spectacle happening in Tasmania, said bioluminescence expert Thomas E. DeCoursey from Rush University in Chicago, Ill. in an interview with Yahoo Canada.

Dinoflagellates blooms are sometimes called "red tides" when red species are involved that produce toxins.These toxins can accumulate in the food cycle, and make shellfish and larger fish dangerous to consume.

Research in just the last decade has begun to solve some of the mystery of how this bioluminescence may be caused. It turns out that an enzyme produced inside the creatures called luciferase, the same substance that makes fireflies glow, is the key, says DeCoursey.

Within the cells are tiny organelles called scintillons that function like tiny factories that are filled with a molecule called luciferin. The luciferase excites the luciferin molecule and causes it to release a photon of light when the creatures become agitated. The movement of the surrounding water triggers electrical impulses within the cells that trigger chemical reactions that generates neon coloured displays. 

And what function does this weird glowing have? Why would it evolve?

While the science community doesnt know for sure, there are a number of theories that centre on having to distract, re-direct or scare off potential predators.

The most obvious idea is that the dinoflagellates do not want to be eaten, so they flash to scare away their predators known as the startle theory, or maybe they light up other prey who might get eaten instead the diversion theory, explained DeCoursey.

There is even the alarm theory that predicts that the flash would attract even bigger predators who might eat the smaller predators, but have little interest in the tiny dinoflagellate.” 

While the phenomenon remains quite unpredictable, scientists do know that it depends considerably on the local environmental conditions.

Typically they need fairly calm water, constant temperatures and in some cases very particular nutrients present, says Marc Zimmer, a biologist at Connecticut College.

The ones in the Caribbean require vitamin B12 from mangroves to make the luciferin that gives off the light, explained Zimmer to Yahoo Canada.

Light pollution and motor boats can kill them, [however] quite often we can see them in the wakes of ships and yachts.

Interestingly, Navy aircraft carriers can leave many mile-long streams of bioluminescence in the wake left behind as the military ships disturb the waters. Jet pilots actually follow these bioluminescence trails back to the carriers while returning from conducting missions under the cover of darkness.

While some places appear luckier than others, it appears there are some beachfront hotspots for catching views of these bioluminescent light shows. Places like the Maldives, Florida Everglades, and the California coastline around San Diego have been noted as particularly stunning.

But one of the brightest neon displays in the world can be found at Mosquito Bay in Veique Island of Puerto Rico.

I have kayaked through the bay at least five times in my life and on each occasion it has truly been spectacular, said Zimmer.

I have seen dinos light up around a fish swimming underneath me, individual dinos caught in my arm hairs twinkled like stars, but the best was a gentle rain in which each rain drop produced a blue luminescent plop of liquid light.