Seasonal meromixis in three hypersaline lakes on Rottnest Island, Western Australia

Abstract

Three of the six permanent hypersaline lakes on Rottnest Island become meromictic 'hot lakes' during winter and spring. An important factor contributing to this transient stratification is a surface input of fresh water from seepages around the lakes, which overlays the existing hypersaline layer. Heat penetrates to the monimolimnion of these clear-water lakes and is trapped by the insulating effect of the overlying less-saline water. The disappearance of the stratification at the onset of summer is thought to be due to reduced freshwater input and evaporation of the less-saline mixolimnion.