then, in 1921, labbé performed a study in which he placed samples of "dunaliella" from saltern brines into a lower salinity environment and observed that the organisms adapted to the new conditions of the fresh water and lost their brown-red pigment and became greener – meaning that the red colour must have originated through very euryhaline chlorophyll-filled cells changing to a red colour in extremely saline conditions after permanently damaging their chlorophyll pigments.  it is now known that there are actually very few "dunaliella" species that can accumulate β-carotenoids and those that do, do so only under high light intensity, high salinity, and limited nutrient growth conditions. cells then can revert back to a yellow to green colour when environmental conditions become less harsh .