Unicellular microalgae cells living in freshwater sources are constantly exposed to stimuli and stresses of all kinds, be it changes in temperature, salinity, drought or pathogenic attacks. With climate change and rapid diminishing glaciers, these variations of the environment will continue to get worse. Sensing, reacting and mitigating the harmful impacts of such drastic environmental alterations becomes a matter of survival for these algal cells. However, how exactly such responses to environmental alterations are implemented by these microbial cells is a question that has made scientists curious. Researchers from the Indian Institute of Technology, Guwahati have now studied the mechanism of lipid accumulation in response to salt stress, in two species of microalgae. The research hypothesized such an increase in lipid production to be a defence mechanism, to prevent shrinking of the cell by osmosis, due to excess salt concentrations outside the cell. Production of specific lipids in such a scenario could help strengthen the cell wall and prevent shrinkage of cells. The researchers observed that salt stress led to an increase in accumulation of lipids or fatty acids by up to 44% in Chlorella CG12 and Desmodesmus GS12. They further studied the effect of various salts like NaCl, KCl, MgCl2 and CaCl2, and found that calcium chloride led to the greatest increase in lipid accumulation in these microalgal species. The researchers suggest that this could be due to the fact that calcium ions (Ca2+) play a crucial role in orchestrating cellular signalling pathways under salt stress conditions, which could eventually lead the cell to further ramp up its synthesis of lipids. The study paves the way to better understand the microbial algae and the different tricks up their sleeves to survive the ever-changing environment.