Algae and diatoms grow within the open waters in Pastos Grandes, the diatoms being represented by oligohaline species such as some "Fragilaria" and "Navicularia" species. Different water surfaces are dominated by different diatom species, distinctions that are only partly mediated by different salinities. Animal species found within the lakes include amphipods, elmids and leeches in freshwater and by "Cricotopus" in saltwater. Additional animals are "Euplanaria dorotocephala", Chironomidae, Corixidae, Cyclopoida, Ephydridae, Harpacticoida, Orchestidae, Ostracoda and Tipulidae species. Similar but different animal species have been found in other local lakes, indicating that they are largely separate systems. The animal flora of such Altiplano lakes is not very diverse, probably due to their relative youth and the harsh and often highly variable climates of the past in the region. Pastos Grandes is one of many endorheic lakes that cover the region. The neighbouring Altiplano was formerly covered by lakes as well during the Pleistocene. After they dried up, the Salar de Uyuni and Salar de Coipasa were left behind. The area of Pastos Grandes has a summer wet climate, with most of the precipitation falling during a wet season in December–March. An estimate for the total precipitation is about . That is, the climate is arid and evaporation rates can reach about . Insolation is high and the temperatures can vary by as much as . During winter, they can drop as far as .