To assess the status of aquatic environments, the Water Framework Directive (WFD) requires chemical analysis of a list of priority substances. However, these analyses provide only very limited information, given the thousands of chemical molecules potentially present in water and the effects of their combinations. New monitoring strategies have therefore been developed to provide a more integrative view of the biological effects of contaminants and their mixtures. While bioassays, biomarkers and biomonitoring are increasingly used to monitor water quality, what are these new strategies and what answers do they provide?

These three methods stem from ecotoxicology, the scientific discipline that studies the effects of toxic substances on the natural environment and living organisms.

Bioassays involve exposing a living model (cell, organism...) to a specific substance or environment, under controlled conditions.

The effects are then then measured in the laboratory according to evaluation criteria (growth, reproduction, DNA modification, etc.).

Bioassay objectives :

• determine the toxicity of a substance
• assess an organism's biological response to a given exposure
• assessing environmental health

Biomarkers are measurable biological characteristics that indicate the presence or effect of exposure to a specific substance. substance. These characteristics may be molecules, proteins proteins, or physiological changes.

Objectives of biomarkers :

• indicate whether an organism has been exposed to a particular toxic substance or environment
• measure the physiological effects of exposure
• monitor changes in the health of living organisms over time

Biomonitoring is to use living organisms as indicators of water quality by studying them in their environment to assess their health and their response to environmental changes.

Biomonitoring objectives :

• assess the overall impact of pollutants on living organisms
• detect unknown or emerging pollutants, whether targeted or not in other analyses
• detect the impact of cocktail effects

These three methods meet different objectives.

Bioassays and biomarkers require, in the vast majority of cases, laboratory laboratory analyses, with delayed results.

Biomonitoring can provide a real-time assessment of the environment under study and can detect harmful effects linked to interactions between interactions between different pollutants. In this sense, it complementary to physico-chemical analyses.