INRA – DNA of diatoms

Photos de différentes espèces de diatomées en microscopie optique (objectif 100 fois à immersion).. © INRA

By Anne Frinault

UPDATED ON 06/21/2017

PUBLISHED ON 04/10/2017


Diatoms: excellent bio-indicators of the ecological status of freshwater courses

These microscopic algae have an external cell wall made of silica whose shape is characteristic of each species. They develop in water courses by forming thin films (biofilms) on the surface of immersed substrates. Because of their considerable biodiversity (more than 100,000 of extant species) and their sensitivity to numerous environmental factors, which varies from one species to another, diatoms can be excellent indicators to monitor the ecological status of freshwater ecosystems. For this reason, the European Water Framework Directive recommends their use as “bio-indicators”. The standardised methods currently employed on a routine basis involve the microscopic observation of samples in order to identify and count the different species present. Depending on the abundance of species and their tolerance to pollution, this then enables the calculation of a quality index, the Biological Diatom Index (BDI). However, these methods remain expensive and time-consuming

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