Modelling the PCB bioaccumulation in the hake (Merluccius merluccius) from the Gulf of Lions (Mediterranean sea)

1
Modelling the PCB bioaccumulation in the hake
(Merluccius merluccius) from the Gulf of Lions
(Mediterranean sea)
X. Bodiguel1, V. Loizeau1, C. Mellon2, F.
Ferraton2
xbodigue_at_ifremer.fr
1IFREMER, BP 70, 29280 Plouzané, France
2IFREMER, B.P. 171, Av. J. Monnet 34203 Sète
Cedex France

• Objectives
• To evaluate the PCB contamination in hakes from
  the Gulf of Lions.
• To establish the bases of a bioaccumulation
  model of PCBs in a female hake.

Study area
Introduction
Polychlorinated Biphenyls (PCBs), are
characterized by a high persistence in the
environment, bioaccumulation by the marine
organisms and potentially toxic character.
Bioaccumulation depends on physical and chemical
properties of the compounds and biological
factors like feeding, growth and reproduction. At
the top of a complex trophic web, the
Mediterranean hake (Merluccius merluccius L,
1758) is potentially exposed to these
contaminants and it is significant to evaluate
its contamination level and contamination
mechanisms.
Evaluate the fate of PCBs in hakes from the gulf
of Lions.

• 44 liver analyses (individuals from 10 to 34
  cm)
• 17 PCBs congeners (CBs) by GC ECD.
• Major occurrence of CB153 and CB138
• Important presence of DDE (metabolite of DDT)

• CB153 230 to 1700 ng.g-1 DW (for a juvenile
  hake of 11,5 cm and a male adult of 34 cm)
• Concentrations 5 to 8 times higher than
• in hakes from the Bay of Biscay
• No influence of the Rhone river between the
  two studied areas
• High inter-individual variability, probably
  due to their physiological properties.
• Assumptions explaining the variations
• Hake lenght (growth)
• Hake sex
• Sexual maturation degree
• Diet evolution

Results
PCB Analysis
CB 153 concentration in the hake livers function
of their length
PCB chromatogram in a male hake liver of 34 cm.
Modelling the PCB bioaccumulation (Dynamic
Energy Budget approach)
Principle
Objective
Quantify the contribution and elimination of CB
153 during all the life of a female hake. Uptake
food Losses excretion, spawning, dilution by
growth.

• Growth model
• Food contained energy is assimilated
  proportionally to the hake surface area and
  stocked in the energy storage compartment
  (constant efficiency).
• Stored energy is allocated to the soma and for
  maturity (for juvenils) or reproduction (for
  adults).
• Maintenance is proportional to the amount of
  structure
• Adults spawn one time each year, at a fixed
  date.
• Starvation during winter
• Initial condition - Egg energy content
• Forcing variables - Water temperature
• - No limiting food

• Coupled contaminant model
• PCB allocation is described likely and
  proportionally to the fixed energy allocation
• PCB food content varying with hake diet
• Stored PCB are allocated to somatic and gonadic
  compartments, proportionally to the energy flow
  to biovolume and gonads respectively. PCB
  mobilisation from reserves is function to the PCB
  storage concentration.
• PCBs are expulsed during the annual spawning.
• Forcing variable - PCB prey concentration
• - Energy
  prey value.

Conceptual diagram
The comparison between growth model outputs and
hake weight and length measurements validates
the growth model during the whole life of a
female hake. The PCB bioaccumulation simulation
seems to be acceptable compared to the few
analysis results.
Results

• Conclusions

• Future model development
• Taking into account bio-transformation.
• Validation for other PCB congeners and other
  contaminants (Hg).
• Extension to male hakes.
• Extension to the hake population and its
  trophic web.
• Contribution of contamination by water during
  breathing.

• Mediterranean hakes are significantly
  contaminated by PCBs. This contamination seems to
  be correlated according to growth, probably
  with the diet evolution and maturation degree.
• The bioaccumulation model simulates rather well
  the growth and contamination of an immature hake
  female.