Lake Retba

About Lake Retba:

• It is also known as Lac Rose (the Pink Lake).
• Location: It is located north of the Cap Vert peninsula of Senegal, northeast of Dakar (Senegal).
• The lake is isolated from the sea by sand dunes.
• Its fresh water comes from the seasonal water table in the dunes, which are higher than the lake. Thus, the sea provides most of the lake’s water and all of its salt.
• The Pink Lake is one of the main tourist destinations in the Dakar region, primarily because of the pink colour of its waters.
• Why is it pink?
  • The pink coloration is due to the proliferation of halophilic green algae (living in a salty environment), Dunaliella salina, which contain red pigments.
  • The algae is associated with halophilic bacteria of the genus Halobacterium.
  • This microscopic alga’s resistance to salt comes from its high concentration of carotenoid pigments, which protect it from light, and its high glycerol content.
  • In fact, Dunaliella salina contains at least four antioxidant pigments (beta-carotene, astaxanthin, lutein and zeaxanthin), which are rich in vitamins and trace elements.
  • When salinity is high, algae with red pigments thrive, and when salinity is low, they give way to other algae rich in green pigments.