——— natural phenomena: the pink lake hillier of australia

We learn from geography classes that water bodies are marked with blue on the map.

But nature likes to mess with us and creates oddities just like Lake Hillier in Western Australia.

With its mere 600 meters in length, Lake Hillier is not one that will impress you by its size. Nor will it impress you by its diverse fishes that inhabit it.

Lake Hillier delights your eye with its pink colour. Moreover, it lies just next to the Pacific Ocean, thus if you watch it from above, the contrast between the mellow pink of the lake and the blue of the ocean is striking.

Why is Lake Hillier Pink?

The exact cause of Lake Hillier's distinctive bubblegum or strawberry milkshake color is not known for sure. Most scientists do agree it has probably something to do with the presence of a specific species of microalgae - Dunaliella Salina.

These salt-loving photosynthetic microorganisms generate energy by using other parts of the visible light spectrum except in orange/red frequencies.

Dunaliella Salina is able to tolerate very high salt concentrations ranging from 0.2% to as much as 35%. These little critters produce the carotenoid pigments, beta-carotene (which are also found in carrots), that are thought to give rise to the bubblegum coloration of the lake's water. 

There are also large amounts of halophilic bacteria and archaea in the salt crusts of the lake that could also be the cause for the lake's interesting appearance. These non-algal microorganisms also produce a similar carotenoid pigment within their cell membranes which is either the main cause or a contributing factor to the lake's overall coloration. 

The Extreme Microbiome Project, part of the Association of Biomolecular Resource Facilities (ABRF), Metagenomics Research Group (MGRG), has been performed on the lake. The researchers used a metagenomic analysis on the lake to find Dunaliella as well as Salinibacter Ruber, Dechloromonas Aromatica, and a few species of the Archaea.

Bacteria and Archaea tend to make up the bulk of the micro-ecology of hypersaline lakes like Hillier. For this reason, the lake's color is thought to be a combination of these factors. 

Lake Hillier isn't the only pink lake in the world, there is another famous one on the coast of Senegal called Lake Retba. 

Whatever the cause, the water does not appear to pose any danger to humans. Swimming in it is not possible anyway, since the island is used only for research purposes and tourists can admire it only from above on helicopter rides.