Pretty in Pink

Explanation: Have you ever seen lakes this color? This week we are at the aptly named Pink Lake near the quaint town of Meningie, in Coorong District and Coorong National Park of South Australia. We are a good 156 km (nearly 100 miles) southeast from the city of Adelaide, along the coast of the Great Australian Bight (bay).

The lakes of this region appear pink, and get pinker later in the summer as they dry out.

What makes them pink is not minerals, but a green micro-algae called Dunaliella salina. The "salina" part of the name refers to the algae's halophile life form, that is, existing and thriving in highly saline (salty) environments. And these lakes are highly saline, indeed.

The algae produces large amounts of carotenoids, which are pink, and which also have highly antioxidant properties. For this reason, the algae is used in dietary supplements and cosmetics.

Mounds of salt form on top of crusts of more salt,
all providing the algae's key habitat.

The algae has been well studied, for over a century. It also serves as a major example of an "extremophile," which is an organism that lives in extreme environmental conditions. Studying extremophiles can be instructure for learning about the possibility of life occurring in extreme conditions on other planets.

But whether we find pink lakes on the moons of Saturn is yet to be seen... For now, we can enjoy this wonderfully interesting organism and environment, right here at home.

Pretty in pink.

Information:
     Cavicchioli, R. 2002. Extremophiles and the search for extraterrestrial life. Astrobiology 2(3):281-292.
     Chidambara Murthy, K.N., A. Vanitha, J. Rajesha, M. Mahadeva Swamy, P.R. Sowmya, and G.A. Ravishankar. 2005. In vivo antioxidant activity of carotenoids from Dunaliella salina - a green microalga. Life Sciences 76(12):1381-1390.
    Oren, A. 2005. A hundred years of Dunaliella research: 1905-2005. Saline Systems 1(2):doi: 10.1186/1746-1448-1-2.

EPOW - Ecology Picture of the Week