1. Concepts and definitions

On the basis of the type of reaction and mode of examination of living organisms subjected to pollution stress, two main categories of organisms involved in pollution biomonitoring are distinguished [1] .

• Bioindicator organisms

  These are sensitive living organisms which, when exposed to pollution episodes, react in a specific way with measurable physiological disturbances of varying degrees. These alterations can range from the molecular to the population level. The information provided by these organisms and integrated over time will therefore depend on both the dose of pollutant received and the pollutant's "toxicity". However, it should be remembered that the physiological disturbances analyzed are never entirely specific,...