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Ecological diagnostic tool for metal contaminated soils : using functional traits of bacteria and macroinvertebrates
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Edité par CCSD -
International audience. A key question in community ecology is to understand how abiotic (e.g. climate, habitatcharacteristics), anthropogenic factors (e.g. contamination), and species interactions drivethe structure and composition of biological communities in the environment. For instance,metal soil contamination is known to cause changes in the taxonomic structure of com-munities living in soils. However, soil functions (e.g. organic matter degradation) are notsystematically affected by metal contamination. To highlight the responses of macroinver-tebrate and microbial assemblages to both ecological factors and metal contamination, wehave developed a generalizable approach based on functional traits (such as morphologi-cal, physiological, and genomic traits) as proxies of functions. We sampled 40 sites in theGrand-Est region of France characterized by different levels of metal contamination. In soilsamples, microbial assemblages were identified through high-throughput sequencing of 16SrDNA while macroinvertebrate communities were sampled using both pit-falls and monolithsand identified to the best possible level of identification (for example, mainly species for bee-tles and spiders). Using existing databases and a literature review, we compiled a databasefor the 2 communities (bacteria and invertebrates) containing respectively 41 and 65 traits,each described by different attributes. Based on these attributes, mean trait profiles of mi-crobial and invertebrate assemblages were deduced from the list of taxa captured and theirabundances within the assemblage. Preliminary results have highlighted the influence ofabiotic factors, such as soil texture, dissolved organic carbon or nutrients, on trait profiles ofthe bacterial communities. Soil contamination selected also macroinvertebrates with specifictraits such as beetles with a one-year life cycle, a fecundity level with an important number ofeggs/female cycle or an herbivorous/detritivorous diet. Finally, we examined the possibilityof using taxonomic and trait-based information on microbial and macroinvertebrate assem-blages as predictors in the random forest models developed to assess the risk of degradationof the two communities by metal contamination, at each site of interest.
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