CESA - Contaminants et Environnements : Métrologie, Santé, Adaptabilité, Comportements et Usages

Variability-adaptation-diversity and Ecotoxicology in Gammarids – GAMMA

Submission summary

Ecotoxicological hazard assessment of chemicals for aquatic ecosystems could be implemented via either a priori approach, with toxicity evaluation of a new compound before its use, or a posteriori approach, with the development of chemical and biological tools for quality assessment of aquatic ecosystems. These approaches are mainly based on the use of more or less standardized laboratory and in situ (caged organisms) biotests for toxic effect assessment of chemicals, environmental samples and natural systems on sub-individual and individual responses in model (surrogate) species. These effects on standard organisms are later translated into potential population-level effects through a series of assumptions and safety factors. The interest of these biological tools has been clearly demonstrated. However, improving the reliability and the ecological relevance of these approaches still constitutes scientific challenges: (1) natural variability of toxicity markers in relation to abiotic factors is a strong limit for their use in environmental risk assessment; (2) the potential divergence of life histories and sensitivities to environmental toxic compounds between experimental and native populations is still an open question. Gaining insight into this source of uncertainty for the ecotoxicological evaluation is of deep concern for its relevance for toxic effects in the field. The soundness of the evaluation is even more questionable as the contamination drives itself the toxicological sensitivity divergence of native populations, in case of adaptation to toxic pressure.
The GAMMA project will answer to scientific questions, which condition the ecological relevance and accuracy of sub-individual and individual markers used for water quality assessment. This work focuses on Gammarus sp, for which we previously proposed and developed a multi-scale approach for in situ toxicity assessment of contaminants (ECCO AO, 2005). The project is structured in 4 tasks. The first one focuses on the variability of basal levels and toxic sensitivity of sub-individual and individual toxicity markers in Gammarus in relation to both environmental factors and populations and species used as source of test organisms. The second task addresses the representativity of effects measured on transplanted organisms in regards with native populations, in order to improve in situ experiments methodology. For the third task, a priori and retrospective approaches will be applied (1) to evaluate the ability of G. fossarum to adapt to metallic environmental contamination and indirect consequences of evolutionary process (fitness costs, loss of diversity) and (2) to identify physiological mechanisms potentially implied in this phenomemon. The last modelling task focuses on the implication of the sources of variability identified in tasks 1 and 3 onto the assessment of contamination impacts at population level in terms of population vulnerability.
The project should bring a significant contribution to improve the ecological relevance of transplantation methodologies for water quality in risk assessment schemes. Findings on between-population/species variability of toxicity markers in Gammarus will highly reduce the uncertainties linked to use of G. fossarum as surrogate species for risk assessment of environmental contaminants at large scale. Specific issues are i) the development of modelling approaches to propose a benchmark for each toxicity markers; ii) improve in situ experiment methodologies to minimize the toxicity marker divergence between transplanted and native organisms; iii) propose population modelling to project individual biological responses (survival, growth and reproduction) in terms of impact on population dynamics; and at last iv) The use of molecular, cellular and histological approaches for assessment of sensitivity difference towards metals between G. fossarum populations will give information on the mechanisms of resistance and adaptation.

Project coordination

Olivier GEFFARD (INSTITUT DE RECHERCHE EN SCIENCES ET TECHNOLOGIES POUR L ENVIRONNEMENT ET L AGRICULTURE - IRSTEA) – olivier.geffard@cemagref.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

Université de Reims Champagne-Ardenne UNIVERSITE DE REIMS
IMBE AIX-MARSEILLE UNIVERSITE
Cemagref INSTITUT DE RECHERCHE EN SCIENCES ET TECHNOLOGIES POUR L ENVIRONNEMENT ET L AGRICULTURE - IRSTEA
AEO UNIVERSITE DE MONTPELLIER II [SCIENCES TECHNIQUES DU LANGUEDOC]

Help of the ANR 299,328 euros
Beginning and duration of the scientific project: January 2012 - 36 Months

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