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

X. Bodiguel1, V. Loizeau1, C. Mellon2, F. Ferraton2

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.

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.

Conclusions

• 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)

Evaluate the fate of PCBs in hakes from the gulf of Lions.

Modelling the PCB bioaccumulation (Dynamic Energy Budget approach)

Introduction

Future model development:

• Taking into account Taking into account bio-transformation. bio-transformation.

• Validation for other PCB congeners and Validation for other PCB congeners and other contaminants (Hg).other contaminants (Hg).

• Extension to male hakesExtension to male hakes..

• Extension to the hakeExtension to the hake population population and and itsits trophic web trophic web..

• Contribution of contamination by water during breathingContribution of contamination by water during breathing..

Quantify the contribution and elimination of CB

153 during all the life of a female hake.

Uptake : food

Losses : excretion, spawning, dilution by growth.

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.

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Study area

Conceptual Conceptual diagramdiagram

PCB chromatogram in a male hake liver of 34 cm.

Mediterranean hakes Mediterranean hakes areare significantly contaminated by PCBssignificantly contaminated by PCBs. This contamination seems . This contamination seems to be to be correlated correlated according to growth, according to growth, probably with probably with thethe diet evolution diet evolution and maturation degree. and maturation degree.

The bioaccumulation model simulateThe bioaccumulation model simulatess rather well the growth and contamination of an immature rather well the growth and contamination of an immature hake female.hake female.

xbodigue@ifremer.fr

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.

Evolution of the CB 153 concentration function of the hake length

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Females measurements

Undtermined sex measurements

Model

• 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 thanin 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

CB153 concentration in the hake livers function of their length

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Undetermined sex

Males

Females

Sector1

Hake weight and length function of their age

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Weight (measurements)Weight (model)Length (measurements)Length (model)

Golfe du LionGolfe du LionGulf of Lion

Sector 2Sector 1

Rhône river

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Golfe du LionGolfe du LionGulf of Lions

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Rhône river

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CB 153 concentration in the hake livers

function of their length

4.5> 20 cm

3 to 1410 to 20 cm

3< 10 cm

CB153 prey concentration(ng.g-1 WW)

Hake length

4.5> 20 cm

3 to 1410 to 20 cm

3< 10 cm

CB153 prey concentration(ng.g-1 WW)

Hake length

Gut

Food Faeces

Biovolume

Storage

Gonadicmaintenance

Somaticmaintenance

PCB PCB PCB

PCB

PCB

Energy

EnergyEnergy

Energy

Energy

Energy

Energy

Reproduction(adults)

PCBEnergy

Maturity(juvenils)Energy

PCBEnergy

Eggs

Gut

Food Faeces

Biovolume

Storage

Gonadicmaintenance

Somaticmaintenance

PCB PCB PCB

PCB

PCB

Energy

EnergyEnergy

Energy

Energy

Energy

Energy

Reproduction(adults)

PCBEnergy

Maturity(juvenils)Energy

Reproduction(adults)

PCBEnergy

Maturity(juvenils)Energy

PCBEnergy

Eggs