Description Tetradesmus obliquus (UTEX 72), Tetradesmus obliquus (UTEX 393), Enallax costatus, Tetradesmus deserticola, Tetradesmus bajacalifornicus, and Fletchneria rotunda are six closely-related species of green algae within the Scenedesmaceae family that have adapted to drastically different environments. Three of these species—T. obliquus (UTEX 72), T. obliquus (UTEX 393), and E. costatus—are freshwater species and three—T. deserticola, T. bajacalifornicus, and F. rotunda—are desert species. Here, we compared how these species respond to water loss and changes in salinity by measuring algal growth and color changes using UV/Vis spectroscopy, and assessing oxidative stress and chlorophyll fluorescence with flow cytometry. Additionally, we explored the genetic basis of pigment production under stress by analyzing transcriptomic signatures associated with pigment biosynthesis in slowly desiccated algae, aiming to identify candidate genes as biomarkers for astaxanthin production.