The dramatic reduction of the Lake Urnia (Iran) water volume in recent years has caused an increase of the salt concentration. As consequence of the higher salinity, the community of photosynthetic organisms inhabiting the lake has changed a well. The dramatic transformation a the deep green waters into a reddish lake is likely caused by the overabundance of the salt-tolerant chlorophycean Dunaliella salina, which is able to accumulate large amounts of carotenoid pigments that produce the pink-red tones in the water. The remarkable change in the water coloration has been noticed even by the NASA's satellite systems
The preceding deep green coloration was not a good indicator of the Lake Urnia healthiness. It is probable that the water was previously contaminated with organic compounds that favoured the proliferation of green algae and cyanobacteria. Sadly, both poor management and increasing global temperatures have caused changes in the physicochemical and ecological conditions of the Lake Urnia, first promoting green algal blooms and, more recently, favoured the proliferation of D. salina and the astonishing coloration shift. Large concentrations of algae in freshwater bodies are not good news at all.