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determination. For instance, in the black tiger shrimp
Penaeus monodon
, Tu et al. (2012)
report that the effect of the pesticide deltamethrin was independent of temperature
and salinity. Moreover, in two invertebrates widely used in estuarine studies, the clam
Scrobicularia plana
is more sensitive to confounding factors than the ragworm
Nereis diver-
sicolor
(Solé et al. 2009; Kalman et al. 2010; Fossi Tankoua et al. 2011).
However, AChE activity has an interesting potential as a biomarker of ecological inter-
est since it is clearly linked to effects at higher levels of biological integration, particu-
larly behavior that is important for the normal functioning of individuals and populations
(Chapter 10) and even for survival.
The inhibition of ALAD is a specific and sensitive biomarker of pollution by lead, rec-
ognized in official monitoring strategies but with no ecological relevance. For instance, in
different areas of a river contaminated with Pb mine tailing in Missouri, USA, Overmann
and Krajicek (1995) showed that enzyme activity of snapping turtles
Chelydra serpentine
was depressed by 94% in the most impacted site. Despite substantial reduction in enzyme
activity associated with high Pb concentrations in tissues, the physiology of the snapping
turtles was not seriously affected.
Cellular pathologies triggered by chemical exposure may be early warning signals of
deleterious effects on flora and fauna. Such responses may be particularly useful biomark-
ers if they are precursors of diseases, directly related to potential risks (Bannasch et al.
1989; Hinton and Lauren 1990; Köhler
et al. 1992; Moore et al. 1994; Regoli 2000; Galloway
et al. 2002; Köhler et al. 2002; Moore 2002; Carajaville
et al. 2003; Marigomez and Baybay-
Villacorta 2003). The association of histocytopathological biomarkers with biomarkers
representing different levels of biological organization may be of great interest in order
to understand the complex machinery that can lead to serious impacts on reproduction,
growth, and survival. In some cases, histocytopathological biomarkers reveal not only
structural changes but also functional changes. Reviewing the application of histocyto-
pathological biomarkers in marine pollution monitoring, Au (2004) has highlighted the
symptoms that are the most highly ecologically relevant (Table 4.3).
Li et al. (2009), who have observed histopathological changes and morphological altera-
tions in intestine and gills of medaka (
Oryzias latipes
) exposed to nano-iron, suggest that
effects on the outside wall of the intestine might promote impairments of normal digestion
function. A reduction of the contact surface at the level of the gill epithelium is likely to
occur, thus affecting gas and ion exchange, whereas a breakage occurring on the surface
of gill filament and the secondary gill lamellae might provide a direct invasion route for
exogenous chemicals.
From 1979 to 1982, Yevich and Yevich (1994) observed abnormalities of the byssus organ
in mussels
Mytilus edulis
collected from a limited area (Prudence Island, Narragansett Bay,
USA) but were unable to find the causative factor of the disease. In March 1981, there was
a massive kill of mussels. In the byssus-bearing scallop
Chlamys varia
exposed to sublethal
doses of silver in the laboratory, histological examination showed that the secretion of
byssus threads was inhibited. A large number of individuals lost their byssus and became
unable to attach themselves to the substratum (Berthet et al. 1992).
Disruption of sensory system function (e.g., Hansen et al. 1999; Johnson et al. 2007) may be
responsible for the absence of detection of environmental pollutants, thus leading to inappro-
priate behavioral responses since once detected, avoidance (escape, valve closure in bivalves)
allows a reduction of exposure, limiting toxic effects and improving survival (Chapter 10).
In addition to alterations of liver ultrastructure, the brown trout (
Salmo trutta f. fario
)
studied by Triebskorn et al. (1997) showed a significant decrease in swimming velocity
in a highly polluted stream, perhaps as a consequence of less energy being available for
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