Aucun titre de diapositive

1
The GEMCO PROJECT -2- The foodweb model
ABARNOU, A.(1), LOIZEAU, V.(1), ROMAÑA, L.A.(2),
BAART, A.(3), van HATTUM, B.(4), THOMAS, P.(5)
(1) IFREMER, Direction de lEnvironnement et de
laménagement Littoral, Ecologie Côtière, B.P.
70, F-29280 PLouzané (2) IFREMER, Direction de
lEnvironnement et de laménagement Littoral,
Polluants Chimiques, B.P. 330, F-83507 La
Seyne/Mer (3) WL/DELFT Hydraulics, Marine and
Coastal Management, P.O.Box 177, 2600 MH Delft,
The Netherlands (4) VRIJE UNIVERSITEIT AMSTERDAM,
Institute for Environmental Studies, De
Boeleaan,1115, 1081 HV Amsterdam, The
Netherlands (5) ATOFINA , Direction Sécurité
Environnement, Cours Michelet, La Défense10, F-
92091 Paris La Défense
Key-words virtual estuary, risk assessment,
predicted environmental concentrations,
modelling, trophic chain
The GEMCO estuarine modelling project sets out to
predict concentrations of contaminants in
estuaries and subsequent bioaccumulation with a
view to its use in marine risk assessment. The
project is in its early stages and no results
have been obtained so far. This poster is
presented with a particular attention to the
foodweb aspects of the model. The project aims to
generalize existing bioaccumulation models to
other chemical compounds that could reach
estuarine organisms.
General objective
Structure of the project and role of partners
The GEMCO project (Generic Estuarine Modelling
system to evaluate transport, fate and impact of
COntaminants) aims to build an user-friendly
software application for the evaluation of
concentrations of given chemical substances in
water, suspended particulate matter (SPM),
sediment and biota in any european estuary
predefined by its main physical, physico-chemical
and biological characteristics.
The GEMCO model includes two interacting
sub-models 1. An abiotic model which predicts
- the substance concentrations in abiotic
compartments (water, SPM, sediment)
- the SPM distribution and the Primary
Production, 2. A foodweb model which
calculates concentrations of these
substances in species using data generated by the
first sub-model. The FW model relies upon the
biological processes . This generic model will
be validated by data from previously studied
estuary (e.g.Scheldt, Seine)
Data base measurements, processes

G
E
Foodweb
model
CD, CP, CSed
M
Ifremer
Brest
C

SPM
Validation
IVM Amsterdam
Primary Prod
O
CBiota
Characteristics
estuary organisms chemicals
VIRTUAL ESTUARY MODEL





PEC in water sediment and biota

The starting point bioaccumulation models
PCB bioaccumulation model in marine and coastal
foodwebs
Model
equation
x
5

dCi/dt Ri . Aiw . Cw Fi. Pij .aij . Cj -
(Ei Gi Repi Mi) . Ci






Limanda limanda
x
x3
4
For each organism, the concentration of a
contaminant results from a mass balanced budget
between uptake via respiration and feeding and
their decrease by dilution growth, excretion,
metabolization. The rates of biological processes
depend on the weight of the animal (age
dependent) and of environmental conditions (TC,
O2, ). Metabolization of persistent compounds
such as PCBs can be considered to be negligible.


x
.
2
Bathyporeia pelagica
Pectinaria koreni
.
x
1
Acrocnida brachiata
Tellina
fabula
Sediment
- concentrations in water (dissolved), SPM and
phytoplankton are forced variables -
environmental conditions (temperature, dissolved
oxygen, chlorophyll,...) vary seasonally -
biological functions (reproduction, growth, ...)
depend on environmental conditions
Phytoplankton
The dab
foodweb

a
coastal benthic foodweb
Validation of the PCB bioaccumulation models
ng.g -1 d.w.
ng.g -1 d.w.
Calculated concentrations Measured concentrations
400

300
Calculated concentrations
Measured concentrations
200
100
0
CB28
CB52
CB101
CB118
CB153
CB180
CB138
The
seabass foodweb

Dynamic
model of PCB contamination
PCB distribution in dab
an
estuarine pelagic foodweb
in
seabass
The further step the virtual estuary model.
This FW model should be able to predict
concentration of chemicals in the species ,
whether
bioaccumulated or not, which live in main
european estuaries. Initial research will be
directed at answering the following questions.
4. Processes. How the key-processes should be
represented by simple and generic equations ?
Should metabolization be considered as a function
depending on compounds and species ?
1. Estuarine context. The physical (bathymetry,
sediment, ...) and physico-chemical features
(salinity, SPM,...) of the estuaries determine
the species distribution and the structure of the
foodwebs. How many types of foodwebs are to be
considered ? which one, benthic and/or pelagic,
freshwater, estuarine and/or marine foodweb. ?
2. Species. Which are the target-species ? Are
they selected according to their biomass, their
commercial value, their role in the trophic chain
or their sensitivity to chemicals ? How many
species need to be included ?
3. Contaminants. How the substances will be
choosen according to their hydrophobicity (Kow)
and their persistence (half-lifes) ? How
metabolization will be described, depending on
the species and on the chemical compounds ?
Expected results 1. Processes/parameters the
foodweb model will highlight the mains processes
acting on the distribution of chemicals in
organisms and the relative importance of
these processes on the fate of contaminants in
biota. 2. Concentrations and chemical risk
assessment the foodweb will predict
concentrations of chemicals in biota and their
variations. These PEC in biota (PEC
predicted environmental concentrations) are to be
compared with PNEC (predicted non effects
concentrations).
Acknowlegements