Reconstructing paleoenvironments of inland waters can provide insight into how climatic change and human impacts have affected the ecosystem.  Paleoliminologists study the change in the number of diatoms and other microfossils within sediment cores to indicate environmental impact.

Diatoms are among the most common types of phytoplankton, and originated more than 200 million years ago.  They are commonly monitored when studying water quality, both past and present, because of their sensitivity to a variety of ecological conditions.