Diatom method

Achnanthes laevis (Oest.)
Cymbella mesiana Cholnoky
Diatoms are unicellar algae with golden-brown photosynthetic pigments. Their cell wall is silicified to form a frustule, comprising two valves, one overlapping the other like the lid of a box.
Diatoms are the dominant marine primary producers and play a particularly important role in the carbon, silica and nutrient budgets of the modern ocean.

Diatoms distribution
Diatoms are autotrophic and form the basis of food chains in many aquatic ecosystems. Different species occupy benthic and planktonic niches in ponds, lakes, rivers, salt marshes, lagoons, seas and oceanic waters, while some thrive in the soil, in ice, or attached to trees and rocks.
peat
diatomite
sapropeles
sand
clay

Reconstructable parameters
Physical factors:
Temperature
Luminance
Mixing properties
Ice cover duration
Chemical factors:
pH
Nutrients
Salinity
Organic carbon
Biological factors:
Mutualism
Parasitism

The formation of diatom-rich deposits

Salinity Reconstructions from
Continental Lakes
Figure: Lake-level record from the Willandra Lakes, Murray
Basin, southwestern New South Wales. Modified from Bowler JM (1998) Willandra Lakes revisited: Environmental framework for human occupation.

References
Armstrong H., Brasier M. Microfossils. – John Wiley & Sons, 2013.
Elias S. Encyclopedia of Quaternary science. – Elsevier, 2006.
Л. Б. Назарова. Биологические индикаторы в палеоэкологических исследованиях, Казанский ун-т, 2013.