Modelling - alternative resource fo r oil risk assessment?
Viaene Karel
Lisette de Hoop2, Jan H endriks2, Frederik De Laender3 and Colin R. Janssen1
1 GhEnToxLab, Ghent University, J. Plateaustraat 22, B-9000 Ghent, Belgium
E-mail: karel.viaene@ uqent.be
2 Institute fo r Water and W etland Research, D epartm ent o f Environm ental Science, Radboud
University Nijm egen, PO Box 9010, NL-6500 GL, Nijm egen, the Netherlands
3 Nam ur University, Research Unit in Environm ental and Evolutionary Ecology, Belgium
Crude oil can be introduced into the marine environm ent via natural seeps a n d /o r human activities.
Events like the Deepwater H orizon oil spill show the need to assess the effects o f crude oil on
marine biota. Q uantitative inform a tion on the effects o f oil on ecologically relevant endpoints such
as survival and reproduction is im p o rta n t fo r risk assessment. However, few e xperim ental studies
have assessed the im pact o f oil co nstitu en ts on these endpoints. Models may be helpful to assess
effects o f oil on the survival and reproduction o f aquatic organism s th a t have remained untested.
Yet, u ntil now, a generic m odel qua ntifyin g accum ulation and effects o f oil co nstituents is lacking.
The goal o f the cu rren t study was therefore to develop a m odel, applicable to a wide range o f
species, to q u a n tify the bioaccum ulation o f oil co nstituents in aquatic organism s and to estimate
the corresponding effects on th e ir survival.
We predicted the bioaccum ulation based on o rg an ism ’s properties such as wet w eight, lipid content
and rate constants o f the chemical. The octanol-w ater p a rtitio n co efficie nt (K ) o f the chemical was
another key m odel parameter. Predicted body burdens were used in concentration-response
fu nctio ns to calculate m o rta lity rates. To assess th e ir accuracy, we applied the models to published
data fo r d iffe re n t species and oil constituents, and com pared our m odel predictions w ith observed
values.
As an exam ple, we estim ated the survival o f the am phipod H yalella azteca exposed to five
fluoranthene concentrations. The m o rta lity rate predicted by the m odel was used to sim ulate the
surviving fra ctio n o f a H. azteca population. M o rta lity due to fluoranthene is accurately predicted
fo r the highest concentration (2 5 0 p g /l) but is underestim ated (up to 20% deviation) fo r the
6 2 .5 p g /L and 1 2 5 p g /L treatm ents. However, considering th a t the OMEGA bioaccum ulation model
requires lim ited data in p u t and th a t general oil to x ic ity values were used to predict the effects o f
pyrene, it can be concluded th a t th is approach shows potential fo r the data sparse risk assessment
o f oil.
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