species in field studies [26–28]. This fish species is common and widely distributed
throughout Europe, in both clean and polluted freshwaters [29]. The abundance
growth rate is stable in France, and feral chubs in the Seine River occur in satisfactory numbers to allow ecotoxicological field studies. Previous studies have
highlighted the high sensitivity of chubs to pollutants, with high levels of DNA
damage and high EROD (ethoxyresorufin-O-deethylase) activity [30–32] in polluted
freshwaters.
Aquatic invertebrates such as filter feeders (bivalves) or detritivorous species
(amphipods) are good sentinel species. Bivalves can concentrate and retain contaminants in their tissues for a long time, which represents a valuable integrative
characteristic. Among continental bivalves, studies are mainly based on a model
organism, the zebra mussel Dreissena polymorpha, which has proved its value
[33]. D. polymorpha, originating from the Ponto–Caspian region, is characterised
by its abundance and widespread distribution in European and North American
rivers, great filtration capacities leading to high levels of xenobiotic accumulation
and good tolerance to environmental stressors [33]. As regards amphipod crustaceans, the genus Gammarus plays a key role in food webs such as the common
shredder, playing a major role in leaf-litter breakdown. The reduction in its feeding
activity is directly correlated with the reduction in the processing of leaf litter
[34]. Furthermore, in Gammarus spp., the ingestion of leaves leads to the assimilation of energy and the production of faecal pellets. Gammarids and their faeces are a
food resource for many aquatic species. Since Gammarus fossarum is widespread in
Central and Eastern Europe, this common species has been defined as a very good
candidate to study the impact of chemical stressors.
In accordance with their sedentary lifestyle, individual responses of the invertebrates used as biomarkers may be correlated with the quality of the sampling site,
thereby allowing for the development of early warning and sensitive diagnosis tools
exhibiting high ecological relevance [35]. Biomarkers related to energy metabolism
[36] and immune functions could be useful prognostic tools, bearing in mind the
close relationships existing between the energy balance and the immunity status in
the health of organisms. Concerning population preservation, biomarkers relative to
reproductive processes are undoubtedly relevant and promising. Regarding field
studies, D. polymorpha and G. fossarum could be used not only in passive
biomonitoring but also in active strategies. In fact, the caging of individuals from
the same population (and a fortiori the same species) in different sites (1) limits or
avoids the influence of intrinsic parameters and (2) exposes organisms for a controlled time period, so that recent contamination can be evidenced. As for the
contamination level or associated biological effects, several studies have underlined
the value of the active biomonitoring approach using D. polymorpha [37–39] and the
amphipod G. fossarum [40, 41]. Therefore, they constitute valuable bioindicator
species, largely used as a freshwater biomonitoring tool [35, 42, 43], as illustrated in
the next sections by studies undertaken in the PIREN-Seine programme.
Experience Gained from Ecotoxicological Studies in the Seine River and. . .
251
throughout Europe, in both clean and polluted freshwaters [29]. The abundance
growth rate is stable in France, and feral chubs in the Seine River occur in satisfactory numbers to allow ecotoxicological field studies. Previous studies have
highlighted the high sensitivity of chubs to pollutants, with high levels of DNA
damage and high EROD (ethoxyresorufin-O-deethylase) activity [30–32] in polluted
freshwaters.
Aquatic invertebrates such as filter feeders (bivalves) or detritivorous species
(amphipods) are good sentinel species. Bivalves can concentrate and retain contaminants in their tissues for a long time, which represents a valuable integrative
characteristic. Among continental bivalves, studies are mainly based on a model
organism, the zebra mussel Dreissena polymorpha, which has proved its value
[33]. D. polymorpha, originating from the Ponto–Caspian region, is characterised
by its abundance and widespread distribution in European and North American
rivers, great filtration capacities leading to high levels of xenobiotic accumulation
and good tolerance to environmental stressors [33]. As regards amphipod crustaceans, the genus Gammarus plays a key role in food webs such as the common
shredder, playing a major role in leaf-litter breakdown. The reduction in its feeding
activity is directly correlated with the reduction in the processing of leaf litter
[34]. Furthermore, in Gammarus spp., the ingestion of leaves leads to the assimilation of energy and the production of faecal pellets. Gammarids and their faeces are a
food resource for many aquatic species. Since Gammarus fossarum is widespread in
Central and Eastern Europe, this common species has been defined as a very good
candidate to study the impact of chemical stressors.
In accordance with their sedentary lifestyle, individual responses of the invertebrates used as biomarkers may be correlated with the quality of the sampling site,
thereby allowing for the development of early warning and sensitive diagnosis tools
exhibiting high ecological relevance [35]. Biomarkers related to energy metabolism
[36] and immune functions could be useful prognostic tools, bearing in mind the
close relationships existing between the energy balance and the immunity status in
the health of organisms. Concerning population preservation, biomarkers relative to
reproductive processes are undoubtedly relevant and promising. Regarding field
studies, D. polymorpha and G. fossarum could be used not only in passive
biomonitoring but also in active strategies. In fact, the caging of individuals from
the same population (and a fortiori the same species) in different sites (1) limits or
avoids the influence of intrinsic parameters and (2) exposes organisms for a controlled time period, so that recent contamination can be evidenced. As for the
contamination level or associated biological effects, several studies have underlined
the value of the active biomonitoring approach using D. polymorpha [37–39] and the
amphipod G. fossarum [40, 41]. Therefore, they constitute valuable bioindicator
species, largely used as a freshwater biomonitoring tool [35, 42, 43], as illustrated in
the next sections by studies undertaken in the PIREN-Seine programme.
Experience Gained from Ecotoxicological Studies in the Seine River and. . .
251