Origin of Energy Metabolism Impairments - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 297

reproductive state of individuals) would explain the fluctuations in the measurement of
some enzymatic activities rather more than the direct effect of temperature. This tem-
perature/seasonal effect may represent one factor interacting with chemical stressors.
Enzyme responses to contaminant exposure may vary according to season (Farris et
al. 1988, 1994; Golovanova et al. 1999; Barfield et al. 2001). A more pronounced effect of
cadmium on amylolytic activity has, for example, been observed in the bream ( Abramis
brama ) during the period of heightened functional activity of its intestine (summer), in
contrast to the winter period in which there was no alimentary activity (Golovanova et
al. 1999).
11.6 Digestive Enzyme Activities in Environmental Biomonitoring
The direct relationship between the digestive activities of animals and their access to
energy through food, underlines the relevance of digestive enzymes to indicate the expo-
sure and/or the effect of one or more pollutants on an organism, but also possible implica-
tions for the entire energy metabolism and, consequently, major functions such as growth
and reproduction. This relevance has led to different researchers suggesting that these
enzymes should be measured as biomarkers (Lagadic et al. 1994; Hyne and Maher 2003).
Hyne and Maher (2003) suggested using the decrease in cellulase, α-glucosidase, and
β-glucosidase activities in macroinvertebrate larvae from the Namoi River in Australia as
potential biomarkers for exposure to pesticides.
The measurement of digestive enzyme activities has shown the sensitivity of response
to exposure of organisms to chemical stressors. Significant inhibitions of cellulolytic activ-
ity (cellulase) were observed in different species of mollusk (a bivalve: Corbicula fulminea ;
a gastropod: Mudalia dilatata ) during exposure to copper and zinc in natural conditions or
in the laboratory (Farris et al. 1988, 1994). Furthermore, inhibition of cellulolytic activity
in bivalves ( Corbicula sp.) placed in a river receiving factory effluent enabled the definition
of an upstream-downstream gradient of contamination of the wastewater (Farris et al.
1988). Douhri and Sayah (2010) made a particular study of α-amylase activity in the amphi-
pod crustacean Orchestia gammarellus , at several sites in Tangier Bay. The results showed a
higher rate of amylolytic activity in individuals at sites furthest away from the contamina-
tion sources, in comparison to sites subjected to industrial wastewaters. During passive
biosurveillance carried out on the polychaete annelid Nereis diversicolor at a lightly contam-
inated site (the Bay of Bourgneuf, France) and a multicontaminated site (the Loire estuary,
France), the lowest enzyme activities (amylase, endocellulase) were measured in worms
taken from the most highly contaminated site (Kalman et al. 2009). Similarly, during pas-
sive biomonitoring carried out with the bivalve Scrobicularia plana in the Goyen, Loire,
and Seine estuaries in France (contamination gradient: Goyen < Loire < Seine), the lowest
digestive activities (amylase, endocellulase in both digestive gland and crystalline style)
were measured in clams taken from the most highly contaminated estuaries (apart from
higher amylolytic activities in the Seine estuary) (Boldina-Cosqueric et al. 2010). Whereas
the lowest digestive enzyme activities measured in the Loire and Seine estuaries probably
resulted from exposure to elevated concentrations of contaminants, the authors did not
exclude the associated effect of low food availability at the time of the study. During active
biomonitoring carried out with the bivalve Dreissena polymorpha , the zebra mussel, in the
catchment of the River Vesle (France) (Palais et al. 2012), upregulation of digestive activities