Conclusions: Biomarkers in Environmental Risk Assessment - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 413

Different classes
of pollutants

Hydromorphology

Bioavailability

Mixture Physicochemistry

Ecological
factors

General
conditions
(salinity...)

Population

Organism

Physical medium

Biomarkers Ecologically relevant

biomarkers

Indirect effect

Defense amage Direct effect

(reproduction)

(lysosomal stability
behavior, energy,
genotoxicity,
immunotoxicity)

FIGURE 16.1
Methods for quality assessment of aquatic environments.

characterized by important spatiotemporal changes in temperature, pH, dissolved O 2 , redox
potential, hydrodynamics, and sedimentary processes, plus salinity in the case of estuaries.
Bioindicators at supra-individual levels of biological organization are long-term responses
that often appear when the pollution impact has been at work for years (Figure 1.3). This lack
of both specificity and precociousness is a serious restraint to their usefulness for environ-
mental protection even though their use is imposed in regulations such as the WFD.

16.1.3 Biomarkers

In contrast to these high-level bioindicators, individual and infra-individual responses
used as biomarkers have attracted considerable interest as they are able to constitute early
and sensitive tools for the assessment of environmental health. The methodology of bio-
markers has given rise to a rocketing number of publications, from about 100 in 1991 to
about 3000 in 2007 (Jemec et al. 2010). These authors have reviewed the criteria for the use
of biomarkers in environmental pollution studies:

• The relationship between the level and the duration of exposure and the bio-
marker response must be established.
• The effect of confounding factors, both intrinsic and extrinsic, must be well under-
stood. Infra-individual biomarkers should be detected at lower concentrations of
exposure than individual responses.
• The changes that occur at a given level of organization must be indicative of
changes at the next level (infra-individual toward individual, individual toward
supra-individual).