Consequences of Energy Metabolism Impairments - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 319

Seine

Authie

25

20

15

10

5

0
0.01

0.01 0.02 0.02 0.03 0.03 0.04

L3 (mm)

FIGURE 12.4
Fecundity in N. diversicolor females from the Authie and Seine estuaries, according to the length of first three
segments.

(a) (b)

3.5
3.0
2.5
2.0
1.5
1.0
0.5

3.5
3.0
2.5
2.0
1.5
1.0
0.5

CA2

CA1 CA6

CA5

CA4

CS3 CS4 CS5

CS2

CA3

CS7

CA7

CS8

CA8

0

0

FIGURE 12.5
Population variations in N. diversicolor originating from Authie (a) and Seine (b) estuaries, over a 3-year moni-
toring period.

Could we use the variations in CEA to forecast effects at population level? In Daphnia
magna, which has a very short life cycle, the ecological relevance of such an energy bio-
marker was examined. In this species, exposure to various toxic agents under laboratory
conditions (Table 12.2) resulted in a decrease in the cellular energy budget, along with a
decrease in the available energy (energy reserves) and an increase in the energy used (res-
piration). At the same time, decreases in the size of organisms and offspring number were
noted (De Coen and Janssen 1997, 2003). These research works established a link between
CEA variations identified at the cell level and individual responses having direct conse-
quences on the population.
Over the past 10 years, mathematical models of the effects based on the impact of energy
have been set up, using the DEBtox software package developed in the Netherlands
(Kooijman and Bedaux 1996). These models aim to explain the disruption of dynamic
energy in organisms, in connection with the accumulation of toxic compounds.