Consequences of Energy Metabolism Impairments - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 318

Individuals (PC 1 & PC 2: 56%)

5

AA2

4

3

AJ2
AM4

2

SF2

SA2

1 SJ2

SM3
AM3

AF2

Authie

AS2

SM4

0 AA4

AF4

AA3

Seine SN3

SF4

AN3

SS2

SA3

-1

SA4

AF3

AN4 SF3

-2

SN4

-3

5

-4 -3 -2 -1 0 1 2 3 4

PC 1 (34%)

FIGURE 12.3
Principal component analysis representing on plane 1-2, the observations carried out in the Authie and Seine
estuaries. Initials of each data set include the collection site (A = Authie, S = Seine), the sampling month
(F = February, J = July, M = May, N = November, S = September, A2 = April 2002, A3 = August 2003) and the year
(2 for 2002, 3 for 2003 and 4 for 2004).

contaminant concentrations —and the results of Authie on the negative axis— correlated with high
energy reserves . Besides showing induction of GST resulting from higher contaminant contents,
organisms from the Seine generally had lower energy reserve levels. Organisms from both
sites were also contrasted in the principal plane 1-3 (not shown) with high levels of PCBs and
a lower AChE activity in the Seine compared to the Authie (Durou 2006).
Concomitantly, a survey into the reproduction of these organisms was conducted to
assess more particularly the potential fecundity of females originating from both sites.
In this species, gametes are produced in the coelom and consequently, fecundity largely
depends on body volume. Organisms from the Authie generally had higher energy reserve
levels than those from the Seine, and also had bigger size and mass. Observations revealed
that females from the Seine (impacted site) had lower fecundity than females from the
Authie, in accordance with their smaller sizes (Figure 12.4).
At the population level, structures clearly varied (Durou et al. 2005). During a 3-year
monitoring period, six cohorts (cohorts of individuals) from the Seine (CSx) and eight
cohorts from the Authie (CAx) were observed (Figure 12.5). It is also probable that life
expectancy in the Seine was shorter; the recruitment of a new generation of individuals
appeared concomitantly with the disappearance of the previous generation.
Thus, in the field, responses of biochemical, bioenergy, and reproduction biomarkers
were compared with the population status in N. diversicolor originating from the Authie
and Seine estuaries. The difficulty of using energy reserves as pollution biomarkers
mainly comes from the fact that they provide a “snapshot” of the situation and do not help
to effectively understand the energy investment already made for growth or reproduction
functions. For example, the Seine samples had high levels of energy reserves in the spring,
a period when females reach sexual maturity and can reproduce (Durou and Mouneyrac
2007). Nevertheless, in the spring, animals had smaller size and mass and lower fecundity
than those from the Authie.