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7.4 Conclusions
From the preceding discussion, it can be concluded that the selection of a single species as
a unique sentinel organism is unrealistic. Thus, the choice has to turn toward a set of spe-
cies that can represent at best the various functional aspects of an ecosystem. According
to the specific objectives under consideration, various approaches (described by Figure 7.8)
are possible:
• In an analysis of the environmental risks associated with the discharge of a
xenobiotic contaminant, bioassays can be carried out on various species, accord-
ing to a methodology approved by national and international authorities such as
the European Commission (2000, 2003). After the application of a safety factor,
guideline values can be established, fixing quantitative limits not to be exceeded
in order to protect the quality of the environment. Nevertheless, the evaluation of
risk could benefit from the use of biomarkers in controlled exposures.
• When the objective is the protection of the biodiversity in an area of particular
interest, the use of groups of bioindicator species allows a long-term evaluation of
contaminant effects on the resident populations and communities. The criteria of
absence or presence of sensitive species can be investigated and core biomarkers
of stress can be measured in these organisms, but it will remain difficult to estab-
lish relationships between cause and effect.
• The objectives of the present work are to develop a biomarker tools using senti-
nel species recognized as successful in the manifestation of biomarkers revealing
contamination of the environment, and the resulting damage to the organisms
that will reverberate at the level of the population, the community, and ultimately,
the ecosystem. Their use would be in keeping with the continuity of programs
monitoring the quality of the environment such as “Mussel Watch,” ROCCH or
MED POL, the action plan for the Mediterranean Sea within the framework of the
environmental program of the United Nations.
Bioassays
Indicator species
Biodiversity
lethal and/or sublethal
of the contamination of the
environment
Safety factor
Indicator species
Indicator species of
effects
Risk assessment
Biomarkers of effects
Presence/absence
Early markers of
stress
Biomarkers
under controlled
exposure
• Behavioral
• Organic
• Physiological
• Cellular
• Molecular
FIGURE 7.8
Different uses of sentinel species according to the chosen objectives.
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