The Earth Story

Gantheaume Point; Broome, Western Australia The Broome sandstone is up to 286 meters thick in the Broome area and contains massive sandstones, cross-bedded sandstones, laminated siltstones, flaser bedding and conglomerates.

Lake Hillier, Western Australia

Last week I posted about the beautfiul blue-green lakes of Mt. Kelimutu, Indonesia here:http://on.fb.me/1ADj7V8. This week I thought I’d cover another colourful waterbody - Lake Hillier.

Lake Hillier is located on Middle Island, part of the Recherche Archipelago which is found off the southern coast of Western Australia. The Lake is particularly striking against the green forest, white sand, and neighbouring turquoise ocean. It’s a small lake, measuring 600 m (1968 ft) by 250 m (820 ft). As with the the nearby Pink Lake in WA and Lake Retba in Senegal, the unusual colour is likely caused by halophytic algae - Dunaliella salina, pink halobacteria and high salt content. However, this cause hasn’t been confirmed at Lake Hiller.

So, how does algae turn water red? When the water level drops, water temperature, light availability and salinity concentration increase. This stimulates the algae to produce and store carotenoids (xanothophylls and carotenes), pigments that help protect the organism against oxidative stress. This causes the ordinarily green algae to appear red or pink.

If you cast back to our Kelimutu Lakes post, in the comments section we mentioned that the colour of these unusually hued lakes are usually affected by seasonal variations related to water level, temperature and chemistry. However, the water of Lake Hillier has a couple of unique features: it retains it’s brilliant colour when bottled (unlike other pink lakes) and the hue is unaffected by seasonal water fluctuations - it stays brilliant pink year round.

Image credit: https://commons.wikimedia.org/wiki/File:LIQENI_HILLIER_-_ROZE.jpg

Past articles: Lake Retba - http://on.fb.me/1C5RHoI Further reading: Lake Hillier - http://hillierlake.com/&http://bit.ly/1LWL2D1 Carotenoids - http://bit.ly/1CCI8k0

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Sunset over Perth

Original caption: