The magic of bioluminescent algae: A spectacle in uMdloti

IOL News

22-04-2025

A few people were treated to the splendour of bioluminescent algae illuminating waves in uMdloti, northern eThekwini, on Good Friday.
Bioluminescent algae rode the waves in uMdloti before crashing near the shore.
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In one of the videos, someone can be heard saying, 'that is insane' as they watched an illuminated wave crash.
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Explaining the marvel, South African Association for Marine Biological Research (SAAMBR) Conservation, Education and Communication executive manager, Maryke Musson, said bioluminescent algae are tiny marine organisms, primarily dinoflagellates, that produce light through a chemical reaction called chemiluminescence, where the conversion of chemical energy to light is highly efficient.
She said it is commonly referred to as 'Sea Sparkle', named after the dinoflagellate (Noctiluca scintillans) which causes bioluminescence when disturbed or agitated.
Musson explained that the glow is caused by a chemical reaction when two key components, a protein and an enzyme, interact when agitated and oxygen is added to the mix. Excess energy is then released as light without generating any heat.
In the deep-sea environment, lack of sunlight has driven the development of bioluminescence as a primary means of communication for hundreds of species of marine animals, she continued.
For dinoflagellates, scientists believe it is more of a result of metabolism, and mostly happens when the water of these specific organisms find themselves in, is disturbed or agitated. That is why you see it in the waves or if you drag your hand through the water, especially during a new moon phase when there is not a lot of external light.
Musson said about 90% of deep-sea marine life can produce bioluminescence. It helps them hunt, hide, attract mates, or confuse predators.
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'One of the strangest (and coolest!) things about bioluminescence is that some animals use it as a form of invisibility. Some marine animals, like certain squid and shrimp, use 'counter-illumination.' They produce light on their undersides that matches the faint sunlight or moonlight from above,' Musson said.
Bioluminescent algae generally produce natural blue or green light, which travels better through water. Some deep-sea fish and squid produce red light, and some jellyfish produce predominantly green light, but blue light is mostly observed.
She said bioluminescence is usually seen in coastal waters across the globe and is often seen in shallow water, such as bays, where plankton can gather.
Musson said Mosquito Bay in Puerto Rico is known as the brightest bioluminescent bay in the world, while in South Africa, bioluminescence can sometimes be seen along the southern and eastern coastlines and is most common along the Garden Route, Eastern Cape and False Bay. It is not often seen in and around eThekwini.
She said most bioluminescent algae are not harmful to humans, animals, or marine life. If bioluminescent dinoflagellates are part of a harmful algal bloom, such as a red tide, toxins can be released into the water, which can cause skin or eye irritation, but this is quite rare. If the water appears red and has a bit of a glow to it, rather stay clear of it.
'You can swim safely in bioluminescent algae as long as it is not part of a harmful algae bloom (red tide). When you move in the water, the bioluminescent algae react to motion, lighting up around your arms, legs, or even splashes, but it won't stick to you and you won't glow afterwards,' Musson said.