Stephanodiscus hantzschii

Stephanodiscus hantzschii is a small centric diatom with a circular valve (frustule) typically 5–20 micrometers in diameter. Its frustule features radial striae (rows of pores) and a central area with areolae (small openings) arranged in a distinctive pattern, often used for identification.^[2] It is primarily found in freshwater environments, such as lakes, rivers, and reservoirs, often thriving in nutrient-rich (eutrophic) waters. As a photosynthetic diatom, it is a primary producer in aquatic food webs, contributing to carbon cycling and serving as a food source for zooplankton.^[3] It is widely used as a bioindicator of water quality, particularly for high nutrient levels (e.g., phosphorus and nitrogen), and is associated with eutrophic conditions.^[5]

The fossilized frustules of S. hantzschii are preserved in lake sediments, making it valuable for paleolimnological studies to reconstruct past environmental conditions, such as nutrient levels and water quality.^[6] It is cosmopolitan, reported in freshwater systems across North America, Europe, and other regions, particularly in temperate climates. Its abundance is often linked to anthropogenic nutrient inputs, making it a key species for monitoring lake eutrophication caused by agricultural runoff or urban pollution.^[4]