Barely 600 meters long and 200 meters wide, this small lake located on Middle Island, the largest island in the archipelago of La Recherche, south of Australia, is famous throughout the world. It is characterized by the unusual pigmentation of its permanent pink waterand even when water is poured into a container, its color remains the same.
This uninhabitable island has dense melaleuca and eucalyptus forest with a narrow strip of dunes to the north, and its small pink lake which attracts millions of tourists each year because of its magical contrast with the green of the surrounding vegetation and the blue of the ocean.
Sequence DNA to solve the mystery
After its discovery in 1802, scientists speculated that its color was due to bacteria that live in the salt crust. While it’s true that this lake is hypersaline, with more than 340 grams of salt per liter of water (eight times saltier than the surrounding ocean), a new study attributes the lake’s unusual color to a combination of microbes.
This study was based on metagenomics, a known method of DNA sequencing present in the samples taken from the lake, making it possible to find the genomes of different microbes. The results of the analysis revealed the presence of microbes from four different domainssuch as archaea, bacteria, viruses and algae, capable of tolerating very high concentrations of salt.
So why is it pink?
Among the microorganisms found, we distinguish Salinibacter ruber, a red-colored bacterium, and Dunaliella salina, a red algae.. The first has a red pigment, and the second contains a large amount of beta-carotene, a chemical that is used in food coloring for its color, which varies from yellow to orange, depending on its concentration. Their coloring is due to carotenoids, pigments that protect them from extreme conditions.
These extreme saline conditions allow for greater microbial sustainabilitywhich may not even be affected by external chemical exposures. The combination of Salinibacter ruber and Dunaliella salina gives Lake Hillier its distinctive pink hue.
Waters that are dangerous if swallowed?
Despite its unusual hue, the lake has no known harmful effects on humans and no toxicity if ingestedyou could even swim in its waters.
It is not toxic, but if its water is ingested in large quantities, it could cause severe dehydration or multiple organ failure.
Although it does not exhibit toxicity if ingested in small concentrations, if we take more than necessary and due to its high salt content, it could cause dehydration mild or severe, which can lead to multiple organ failure and, in the most severe cases, cause death.