Diatom methods | Salinity reconstructions from continental lakes

The species composition of diatoms preserved in lake sediments can be used to infer changes in salinity or conductivity, driven by changes in the balance between precipitation and evaporation through time. This approach works best in topographically closed lake basins in arid or semiarid regions that have limited groundwater flow. The inference of salinity from changes in the species composition of diatoms is based on knowledge about diatom ecological tolerances derived from studying modern lakes, and in most cases salinity inferences can be made with a high degree of confidence. Effective reconstruction of climate from salinity change relies on a good understanding of the factors that control the hydrologic mass balance of individual lakes. Diatom-inferred salinity changes have been used to document Quaternary environmental change from modern and ancient lake basins on all continents and from high to low latitudes. The majority of studies are from the Americas and Africa, where diatoms have been used to document major changes in precipitation associated with global temperature change and changes in insolation at orbital and millennial timescales. Diatoms also have been used increasingly in high-resolution analyses that seek to reconstruct the natural variability of drought under the changing boundary conditions spanning the period from the Last Glacial Maximum to the Holocene.