Biology Reference
In-Depth Information
7.1 Concept of Sentinel Species
Programs involving sentinel species in which data on organisms exposed to contaminants
in the environment are regularly and systematically collected and analyzed, represent a
mechanism used to estimate the risks of contaminants for the health of mankind and/or
that of the environment (NRC 1991).
When a xenobiotic is introduced into an environment (Figure 7.1), its first effects are
observed at the level of the organism, then the population, the community, and ultimately
at the level of the whole ecosystem. The earlier the detection of these disturbances, the
better are the possibilities of remediation and the opportunity to define the contaminant
source, explaining, therefore, the interest shown in sentinel species and in the study of
their biomarkers. Sentinel organisms are indeed particular bioindicators used to reveal
precociously the presence and the toxicity of one or several pollutants in the environ-
ment. Such substances are often bioaccumulated by these organisms, for example, filter-
feeding mollusks, but in particular they provoke changes in biological parameters at
various levels of biological organization (molecular, cellular, physiological, individual,
etc.) leading to dysfunction of variable ecotoxicological importance. Thus, although they
remain present in the environment, particular organisms can reveal changes in their
health status or modifications of their behavior that might have an influence on their
capacity to reproduce and their long-term survival in this environment, potentially lead-
ing to disturbance of the structure and the functioning of the ecosystem.
Abiotic factors
Ecosystem
Biotic factors
Communities
Populations
Organisms
Disappearing/persistence
Sentinel
species
Environment
Bioaccumulation
Modifications of bioligical parameters
Increasing time of response
Inceasing diculty in remediation
Increasing diculty to establish a link with a specific pollutant
Xenobiotics
FIGURE 7.1
Positions of sentinel species in the various levels of biological organization.
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