|Present address:||Mediterrean Institute of Oceanography, Aix-Marseille University, Campus de Luminy, Case 901 Bat.TPR1 entree F 4eme etage, 13009 Marseille|
|Specialization:||Marine Biology and Ecology, Ecological Modeling|
Dynamic Energy Budget theory
Aquatic ecosystems are the recipient of toxic by-products of industrial and agricultural activities (fertilizers, uranium ore leaching, storing of mine tailings, nuclear fuel enrichment processes, transport/industrial accidents etc.) and as such are submitted to chronic rejections of radionuclides which can directly interact with aquatic organisms. Fish are particularly sensitive to such pollution. One possibility is that polluted substrate is converted to polluted biomass which in turn can be consumed by humans. Another possible outcome is the alteration of one or several biological functions which can potentially a ect their reproduction, growth, and/ or survival thus endangering the whole population with consequent economic repercussions.
Uranium is a heavy metal with dual chemical and radiological toxicity depending on the isotopic composition (Barillet et al., 2007) and is generally the main component of the fuel for nuclear power plants. While it is a naturally occurring element, its concentrations in rivers, lakes and drinking wells are increased due to surrounding human activities. I address the problem of how individual level e ects of uranium relate to population level effects by first characterizing the (control) metabolism of a small cyprinid: zebrafish Danio rerio in laboratory controlled conditions and second quantifying eco-physiological uranium induced deviations from the blank. The work is carried out within a conceptual framework which specifies the acquisition of energy by food uptake and its distribution to the major physiological functions of an organism (maintenance, growth and reproduction) considered at all stages of its development: Dynamic Energy Budget (DEB) theory (Kooijman, 2010). The strength of working with a general unifying theory is maximising extrapolation power.
I build upon extensive prior work which already demonstrates genetic, molecular and individual level e ects of exposure to waterborne uranium on zebrafish. In short; uranium impacts enzymatic activity linked to cellular anti-oxidative stress defence systems (Barillet et al., 2007, 2005) and modifies the expression of genes involved in anti-oxidative stress (Lerebours et al., 2009). Studies conducted at the individual level show that uranium reduces larval growth and survival (Bourrachot et al., 2008) as well as adult reproductive output (Bourrachot, 2009). The connection between observations specific to each experiment and life-cycle and population level consequences however remains weak. Processes predominantly governing behavior of the system at each biological scale (molecular, individual, population) differ and we still need to understand links between observations performed at the different spatial/ temporal scales.
The standard DEB model will be parameterized using existing data from the literature as well as additional data acquired during the project. Individual properties impact population dynamics (Kooijman, 2010). Phase two is determining the predominant mode of action of uranium on the metabolism of individual zebrafish, i.e. analysing toxicity data with the model to quantify effects on the metabolism. These effects may be substantiated by parallel histological analysis of a relevant tissue. The final aim is to look at how these effects translate to effects on population level statistics such as the population growth rate using the characteristic equation.
Barillet, S., Buet, A., Adam, C., and Devaux, A. 2005. Does uranium exposure induce genotoxicity in the teleostean Danio rerio?First experimental results. Radioprotection, 40: S175-S181.
Bourrachot, S. 2009. Etude des effets biologique de l exposition à l' uranium chez le poisson zèbre (D. rerio). Impact sur les stades de vie. PhD thesis, L' Université Aix-Marseille I - Université de Provence.
Bourrachot, S., Simon, O., and Gilbin, R. 2008. The effects of waterborne uranium on the hatching success, development, and survival of early life stages of zebrafish (Danio rerio). Aquatic Toxicology, 90: 29-36.
Kooijman SALM. 2010. Dynamic Energy Buget theory for metabolic organisation. Cambridge, Cambridge University Press.
Lerebours A, Gonzalez P, Adam C, Bourdineaud J-P, Camilleri V, Garnier-Laplace J soumis. Gene response of the zebrafish (Danio rerio) exposed to environmentally relevant waterborne uranium concentrations.
My thesis won the Prix de thèse 2011 of Aix-Marseille University.
This is the symposium that completes my project