Why Is Lake Hillier Pink?

The pink-colored waters of Lake Hillier are caused by the presence of the Dunaliella salina microalgae.

5. Why So Pink?

Lake Hillier, a 600-meter long, unique, saline lake with a bubble gum pink color, is located near the shores of the Middle Island of the Recherche Archipelago in Australia, off the southern coast of Western Australia. Though, as of yet, no conclusive proof exists to firmly explain the source of the pink color of the lake, investigations indicate that secretions from certain microbes inhabiting the lake waters could contribute to the pink color of the water. When viewed from above, the lake’s pink color provides a stark contrast to the surrounding blue waters of the Southern Ocean from which it is separated by a narrow strip of land.

4. Historical Role

Lake Hillier was first discovered and named by the English navigator and cartographer, Matthew Flinders, who arrived at the Middle Island in 1802. He was the first to report this lake when he observed it by climbing the highest peak on the island. In 1803, he named the lake as Lake Hillier after a crew member of his expedition team who died of dysentery that year. In 1889, another European, Edward Andrews, arrived on the Middle Island with his sons with the idea of extracting salt from Lake Hillier. Several attempts were made in the next few years to utilize the lake for salt mining but various factors including the relative toxic properties of the salt extracted from this lake, discouraged such salt mining activities in the lake. The salt miners thus evacuated the area and many years later, Lake Hillier became a part of the Recherche Archipelago Nature Reserve, thus achieving a protected status. Now, the lake and its surrounding habitat became accessible only to scientists working in the region, while the public visitation to this area was highly restricted.

3. Modern Significance

Lake Hillier is treated as a natural wonder and hence receives many visitors by air who fly over the lake to catch a glimpse of the bubble gum pink color of the water body. Lake Hillier and its surrounding habitat also serve as the base of a significant volume of scientific research. The lake and its habitat is studied extensively by the Association of Biomolecular Resource Facilities. The Extreme Microbiome Project, encompassing the investigation of the microbiota of the lake which survives under the extreme salty conditions, is the prime subject of study here. This study attempts to unravel the mysteries of the microbial world and the unique microbial adaptations to high salt conditions.

2. Habitat and Biodiversity

The Lake Hillier is inhabited exclusively by only microorganisms. The Dunaliella salina is the microbial algae species inhabiting the lake which is held responsible for catalyzing reactions that result in the pink color of the lake. Pink halophytic bacteria also live in the salt crusts around the lake which could also contribute to the pink color of the lake. Lake Hillier is surrounded by a rim of woodland with eucalyptus and paperback trees as the dominant vegetation and is separated from the sea by sand dunes covered by vegetation. Birdlife International has declared the area around the lake as an "Important Bird Area", due to the high biodiversity of avian fauna in this region.

1. Environmental Threats and Territorial Disputes

Currently, the Recherche Archipelago Nature Reserve, a highly protected area in Australia, includes the Lake Hillier within its boundaries. This nature reserve is limited to tourist visitations and only licensed operators are allowed to operate here. Thus, as of now, the lake and its surrounding habitat are free of human intervention and anthropogenic threats. Only scientists are allowed to carry out research and work on the lake.


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