Waters of Irans salty Lake Urmia, which are normally aquamarine or various shades of green, became blood red, as captured by NASA. According to scientists, the color change was caused by microorganisms.
The Moderate Resolution Imaging Spectroradiometer (MODIS) onNASA's Aqua satellite recently captured a transition inthe color ofLake Urmia betweenApril and July 2016. On April 23, the water was green asusual; byJuly 18, the lake started tolook more likea wine spill.
Like the Aral Sea, once the fourth largest salty lake, Lake Urmia has shrunk rapidly duringthe pastdecades. The results fromsatellite imagery indicated that the lake has lost about70% ofits surface area overthe last 14 years, scientists say. As it becomes smaller, it grows saltier, especially duringthe summertime. That is when the microorganisms show their colors.
According toscientists, there are two main groups oforganisms involved inthe color change: a family ofalgae called Dunaliella and an archaic family ofbacteria known asHalobacteriaceae.
"In the marine environment, Dunaliella salina appears green; however, inconditions ofhigh salinity and light intensity, the microalgae turns red due tothe production ofprotective carotenoids inthe cells," explained Mohammad Tourian, a scientist atthe University ofStuttgart. Carotenoids are organic pigments responsible forbright red, yellow and orange hues.
Other scientists emphasize the role ofHalobacteriaceae, a group ofbacteria, which release a red pigment that absorbs light and converts it intoenergy forthe bacteria. When populations ofthe bacteria are large enough, they can stain bodies ofwater.