Sea Sparkle – Extreme Bioluminescence in Tasmanian Waters

Text by Dr. Lisa-ann Gershwin and Fiona Walsh

Images by Alison Painter, Dallas Stott, Geraldina Dijkstra, Jonathan Esling, Leoni Williams, Nic Fitzgerald, Paul Fleming, Theresa Ockenden, Dave Reynolds, and Nick Dobinson

We mere mortals have marvelled at Mother Nature since time immemorial: sunsets and sunrises, lightning, hail storms, eclipses, aurorae, rainbows… and even snowbows for that matter. Nature’s art has inspired painters, poets, lovers, and the forlorn, and provided us all with a means of feeling a connection to something so much bigger than ourselves. This connection – this attraction to nature – transcends cultural boundaries, political paradigms, and the passage of time.

And it was has been on full, electric blue display across southern Tasmania.

 

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Our story begins with a handful of aurora photographers, who were out on their regular Friday night aurora hunt. The skies were clear, the moonlight was dim, and the weather mild; unfortunately the aurora failed to develop. As they were heading home, they noticed a strange yet illuminating glow coming from waves lapping in the distance. The tide was too far out to get a closer look, yet curiosity had taken hold and a plan was made to return the next night on the hunt for the glowing stuff. And the rest, as the saying goes, is history.

Photos were posted, the story went viral, media frenzied, young and old flocked to the beach, people flew in from the mainland to see … In the blink of an eye – or really, in a flash of light – Noctiluca became a household word and Tasmania became a bucket-list destination.

 

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The phenomenon of bioluminescence – or sea sparkles – is caused by organisms that make their own light with a chemical reaction inside their body. In this case, the organism is a tiny dinoflagellate called Noctiluca scintillans, Latin for “sparkling night light”. Dinoflagellates are a type of phytoplankton (phyto = plant, plankton = drifter); however, they aren’t true plants, rather, they are microscopic single-celled algae. They are like seaweed, but much smaller. Rather than make their own energy like a plant does, they consume organic matter floating around them, including other single-called organisms like plankton and even fish eggs.

 

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Many types of dinoflagellates are bioluminescent, and may produce different colours of light. Noctiluca flashes or glitters with brilliant neon blue. Singly, each individual emits a tiny speck of light, but en masse, they can light up a beach with an eerie other-worldly glow. Their bioluminescence are usually be observed in three different ways: a dull glowing band along the shore that defines the edge of the concentration, brilliant flashes when disturbed such as by crashing waves or dancing enthusiasts, and gentle twinkling where individual Noctiluca cells have been washed up on the sand.

So bright is their light, in fact, that during World War II, the Japanese dried dinoflagellates into powder and issued envelopes of it to their troops. At night on the front line, the soldiers would pour a bit of powder into their hand, spit on it, and rub it between their palms, giving them enough light to read their maps by without giving away their location.

 

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So what has triggered Tasmania’s recent sea sparkling? The present bloom had been building for a few weeks following rains that washed nutrients into the water; dog poo on the sidewalk and Seasol in Grandma’s garden act like fertilizer for algae when storm runoff gets into the sea. The bloom came to light when the winds blew it into accessible locations, and this extreme bioluminescence event has now been reported across Southeast Tasmania from Kingston, Howden, Battery Point, Howrah, Lauderdale, Eaglehawk Neck, and many points in between. Protected areas, surf beaches … you name it, people are seeing Sea Sparkles there. Many of the most incredible photos were taken at South Arm near the neck, where the northerly breeze blew the Noctiluca into Ralph’s Bay and concentrated them against the shore at the bottom of the bay. The neon blue waves were plainly visible to passing traffic.

 

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This influx into such easily accessible areas has provided a unique opportunity for people to interact with nature in a completely unexpected and thrilling way. A hand dipped in the water comes out glowing an electric blue. A handful of sand thrown over the water produces a spray of sparkles … and then an explosion of light. Sand poured through the hands looks like molten blue light. Footprints at the water’s edge flash then twinkle. A dog splashing in it creates a light show that defies description.

 

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While the spectacular unretouched photos made their way across the world’s headlines and mainlanders booked flights to come see this natural wonder, there is another, more sinister side of this species that is just as surprising as its sparkle: it is a pest. And a bad one at that.

 

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The sad truth is that Noctiluca is one of the world’s most unwanted species. It was first reported in Tasmanian waters in 1994. It is not native here. Its invasive progress has been tracked and studied by researchers at the University of Tasmania, and the story is not a good one. It has spread to more or less every nook and cranny of the Tasmanian coastline, and has recently penetrated the Southern Ocean, expanding ever southward. Periodically when the conditions are right, it blooms into superabundances, the sorts of numbers that are generally only met with in astronomy. Billions. Trillions. Numbers that don’t even have names. In these sorts of numbers, Noctiluca is a killer. As the cells die, they burst and release their ammonia-rich contents into the surrounding water. The water becomes toxic and de-oxygenated. Globally, Noctiluca has more fish kills notched onto its belt than just about any other species. Having said that, it is a sight worth seeing as well as a spectacular reminder for us all to explore the world around us. You never know what amazing things you may find.