Seeing images of lakes turning blood red like this one in Camargue, France, can be a bit scary — especially if you have any nagging worries about 2012 actually being the year the world will end.
There's no need to worry, though. It happens every year, and it's completely natural.
"This phenomenon is a result of the salt content in brine shrimp Artemia salina and algae Dunaliella salina. When the salt concentration is very high — which is the case before harvest — the brine shrimp die and saline algae proliferates giving this unusual colour," said Patricia Estebe of Camargue's tourist office.
The Camargue (pronounced ka-marg) is a wetland region along the French Mediterranean Coast known for the naturally-high salt content in the water, and for the most voracious mosquitoes in all of France.
Salt extraction from the area has continued since prehistoric times, and was a major source of wealth for the region in the Middle Ages. Part of the reason for the higher concentrations of salt in the water there today is irrigation drainage for farming. Water levels reach their lowest just before harvest-time, then rebound until spring when irrigation begins again.
This phenomenon has also happened elsewhere.
Back in June of this year, high levels of salt caused a west African lake to turn the color of a strawberry milkshake, and last August, in drought-stricken West Texas, the remaining water in a reservoir turned a deep red color, alarming nearby residents.