Pretty in Pink

Lake Retba, Senegal  Credit:  ©
Lake Retba, Senegal Credit: ©
Micrograph of Dunaliella salina
Micrograph of Dunaliella salina

No photo-shopping here folks…that water is pink! It’s Lake Retba, aka Lac Rose, in the Cap Vert peninsula of Senegal. The pink is caused by the harmless Dunaliella salina halophile (an algae that can live in a very high salt concentration).   These free-floating microbes harvest energy from the sun through the process of photosynthesis.   The color is especially vibrant during the dry season.

Collecting salt on Lake Retba
Collecting salt on Lake Retba

Many salt collectors work 6–7 hours a day in the lake, which has a salt content close to 40% (1.5 times higher than the Dead Sea). In order to protect their skin, they rub their skin with “Beurre de Karité” (shea butter, produced from shea nuts obtained from the Shea nut tree), which is an emollient used to avoid tissue damage.

Dunaliella salina  has shown to be a potential source for large amounts of β-carotene and glycerol. Carotenoids are chemicals with significant commercial interest.  They are used as coloring agents in pharmaceuticals, cosmetics and food. β-carotene is also used in research such as genetic engineering.

There are 8 notable pink lakes on Earth.  Here’s another favorite tourist attraction:

Lake Hiller Middle Island Western Australia  Credit: ©
Lake Hiller Middle Island Western Australia Credit: ©

Middle Island and its pink lake are located in a pristine wilderness. The only way to view this lake is from the air. From above the lake appears a solid bubble gum pink. The lake is about 600 meters long, and is surrounded by a rim of sand and dense woodland of paperbark and eucalyptus trees. A narrow strip of sand dunes covered by vegetation separates it from the blue Southern Ocean. The lake has been identified by BirdLife International as an Important Bird Area (IBA) because it supports significant numbers of native and migratory birds.

It just goes to show how something considered unpleasant – algae – can look so beautiful.


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