Why does Australia have pink and purple lakes?
What colour do you think a lake is, blue? Yes, right. Green? Well, maybe if it has too much algae growth. Pink? Can’t be! After all, there are no strawberries in there, right? Well, you are wrong in your assumptions here. You will see hundreds of pink and purple lakes during a trip to Australia. Take for example, the well-known ones like Lake MacDonnell in South Australia's breathtaking Eyre Peninsula and Lake Hillier in West Australia. They are famous for their stunning pink colour. The pink in these lakes is caused by a combination of factors including high salt concentration coupled with evaporation levels during the summer and algae or bacteria growth.
The secret behind the pink colour
Pink lakes are created by a combination of factors including the continent’s climate and hydrology. Scientists have discovered that pink water bodies in Australia such as Lake Hillier contain both halobacteria and a sort of algae called Dunaliella salina.
Increasing salt concentrations and evaporation levels during the summer cause the temperature to rise and create sufficient light requirements for the algae and bacteria to produce the red pigments beta carotene and bacterioruberin respectively. This gives the lakes a pink and purple hue.
The algae contain a pigment called beta carotene. Remember the pigment which gives the carrot its orange colour? The same pigment present in this algae gives the lakes their pink and purple colour. Similarly, holobacterium present at the bottom of the salt crust in water contains a pigment called bacterioruberin which is even more pinker than beta carotene, making the lakes look like a pink milkshake.
Fading colours
However, the pink colour in many lakes comes and goes, as the conditions alter. For example, Pink Lake, a salt lake in Western Australia’s Goldfields-Esperance region has seen its pink fading in past few years. Even if the lake’s waters were visibly pink historically, they are no rose now.
The concentration of salt in Pink Lake is essential to the pink colour and due to modifications in the natural water stream, decreased evaporation, and salt production, the distinctive colour has disappeared.
Is the water of these lakes toxic?
Despite their unusual hue, the lakes have no known adverse effects on human skin or bodies. One could even swim in its waters. Just make sure you don't have any open wounds as they'll be seeing a lot of salt in them once you take a dip!