Why Did This Antarctic Pond Turn Bright Purple? Scientist Turns To Twitter For Answers


The pond is near Palmer Station and is very close to the ocean. Scott Hotaling/Twitter

An image of a bizarre lilac pool is sparking more questions than answers after a scientist in Antarctica posted it to Twitter.

Scott Hotaling, a PhD student with Washington State University’s School of Biological Sciences, is currently conducting field research in the southernmost continent to study the physiology and genomics of the Antarctic midge (Belgica Antarctica), the largest endemic insect in Antarctica. He came across the “strikingly purple pond” while working on the small rocky Humble Island located just off the coast of Antarctica.


Hotaling told IFLScience that the pond is near Palmer Station and is very close to the ocean. At just around 5 meters (16 feet) above sea level, it appears shallow. When he couldn’t figure out what prompted the bizarre coloring, he turned to colleagues and citizen scientists on Twitter.

Humble Island is known as an important birding habitat with several species of penguins who call it home, according to a survey by BirdLife International. Hotaling adds that he believes that the color may come from penguin colony “input” nearby. Others chimed in, adding that the chalky lavender hue is likely the result of a microbial bloom.

“I'd bet on the bloom being due to purple bacteria (non-oxygen-evolving photosynthetic organisms. If there is no smell of H2S (the rotten-egg smell), then the organisms are growing using light as the energy source and organic matter for carbon,” wrote microbiologist Michael Madigan. Hotaling adds that the area surrounding the pond doesn’t smell bad, at least his team couldn’t smell it over the nearby elephant seals whose “smell is on an entirely different level of horribleness”.


Stefano Amalfitano, a marine ecologist, notes that the pond is an example of “opportunistic extreme microbial water painters” such as psychrophilic purple bacteria commonly found in Antarctica. Other potential colorful catalysts include Halobacterium halobium, Dunaliella salina, or Rhodocylcus purpureus


Regardless of its cause, Hotaling adds that social media can be a great tool in informing science.

“Twitter is awesome! This thread was a great example. We saw something cool, I shared a photo, and we all learned a bunch of new science," he said. "I could see opportunities for detrimental effects but in my experience, it's all been positive.” 

Though many of the scientists on Twitter requested a sample, Hotaling says that he has no plans to follow up on the mysterious purple pond as the permits his team are currently working under do not allow for the collection of samples.

“I'm mostly sharing it in hopes that other folks will develop research or collaborations to work on it and similar habitats in the future!” added the genome biologist.

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