Evaporation is a natural process that removes freshwater from the Earth's surface including streams and rivers, transforming liquid water into water vapor. Increased evaporation over an estuary and decreased freshwater inflows decreases the water in that estuary and increases the salt content. Salt does not evaporate and therefore increases in content in estuaries with high evaporation. Species adapted to a certain salinity range are further pressured when evaporation is high, which occurs during droughts and high temperatures.