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diatoms

The diatoms (Bacillariophyceae) are microscopic, unicellular organisms that form one of the most common groups of algae. Their existence is dependent on presence of the water. They occur in different types of basins , such as seas, lakes, rivers, streams, springs. Diatoms also occur in environments not rich in water like on tree trunks or within the soil. Their cellular wall is built of silica, which is what separates them from other algae. Diatoms are well adapted to changing environmental conditions. Thanks these characteristics they are well preserved in sediments, and thus diatoms are one of the best proxies for reconstructing environmental changes.

There are two groups among diatoms: eurybionthic species, which have wide range of tolerance for different environmental parameters, and stenobionthic species, which have strictly defined environmental requirements. This second group of diatoms is particularly useful in bioindication of water sedimentary environments (Bubak et al, 2006).