Bubble gum pink isn’t a color reserved for just candy. In Australia, several natural-forming, brightly pink-hued lakes attract tourists from around the world every year hoping to take a peek at their out-of-this-world coloration.
And the lakes made their way around the world of the internet in late May 2021 when a user shared four photographs of the lakes to the travel Facebook group, Girls LOVE Travel.
“No way this is really that pink!” wrote Estrada.
Yes, way. As it turns out, Australia is home to at least seven pink-hued lakes, some of which are found inland and others that are nestled against the white sand beaches of the South Pacific.
Perhaps best known is Lake Hilliar. First discovered in 1802 by navigator Matthew Flinders, the lake is located on Middle Island off of the coast of Western Australia. Like the other pink lakes of Australia, it is believed that Lake Hilliar’s vibrant pink color is the result of microalgae called Dunaliella salina. The salt-loving algae produce carotenoids — the same pigment found in carrots — that could help to explain how the lake gets its pink color. According to a 1987 study published in the Journal of Arid Environments, the water of some lakes can turn pink during the warm and dry months of the year when brine concentrations are highest. As water evaporates from the surface of the lake, and the body of water increases in salinity, D. salina develops its reddish pigment.
Researchers with the U.S.-based Extreme Microbiome Project, a scientific effort to characterize extremophiles and novel organisms, studied sediment and water samples from the lake to better understand the organisms that call it home.
“While the pink color is thought to be caused by salt-loving algae, the actual microbial composition of the lake is unknown,” wrote Ken McGrath, national sequencing manager at the Australian Research Facility. “The analysis revealed a surprising range of microbial diversity in the lake, and indicates that many algal, bacterial, and archaeal halophiles contribute to the persistent pigmentation of this pink paradise."
McGrath and his team genetically sequenced organisms found in the lake using what is known as metagenomics – the “fishing net” of genomics that captures everything in the sample, not just the fishing rod looking at a specific question.
A “bigger picture” of what was in the lake revealed that while D. salina is the dominant bacteria in the lake; other archaea — unicellular organisms like bacteria that make up a different branch of the tree of life — were also found in abundant numbers, including salt-loving species and subspecies.
That same year, SciShow host Hank Green described this process as a special adaptation that allowed these microscopic organisms to survive in an otherwise inhospitable environment.
Though the exact mechanism behind Australia’s pink lakes is not completely known, scientists are beginning to understand how such hues can be found naturally on Earth.