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Communication Dans Un Congrès Année : 2022

Microbial indicators and Quality Ratio index for risk assessment in oil contaminated sediments of tropical coast

Résumé

Due to anthropogenic activities, coastal sediments are prone to hydrocarbon contamination, which can be reflected in the microbial community structure and diversity. In order to determine the impact of oil contamination on the microbial assemblages inhabiting the sediment of several stations located around the Sepetiba Bay (Brazil), highly impacted by human activities, several approaches were combined. Chemical contamination factor (CF, n-alkanes [CFn-alkanes] and 16PAHs [CF16PAHs]) and Quality Ratio (QR) index for ecological risk assessment were combined with microbial community characterization (16S rRNA gene sequencing). Oil pollution (CFn-alkanes and CF16PAHs) present a general decreasing trend from the internal to the external sector. The QR, a function of the microbial term (dehydrogenase/esterase enzymatic activities) and the geochemical term (TOC × CF16PAHs/fine-grained content), ranked most of the internal sector stations as moderate and high risk to the local biota. The canonical correspondence analysis, explaining 55% of the microbial community composition variation (ASV level), exhibited the CF16PAHs as the main factor driving the microbial community structure. Phylogenetic analysis revealed predominance of Proteobacteria (54%) phylum with a high abundance of the gammadelta- and alpha-proteobacterial classes (29%, 21%, and 3% respectively), among which diverse members have been described as capable of degrading hydrocarbons. Among the potential hydrocarbon-degrading bacterial taxa, the most prevalent genera were Vibrio (12%), Desulfatiglans (11%), and Bacillus (8%). The cluster correlation analysis revealed prokaryotic taxa resistant in the internal sector, which mainly present anaerobic metabolisms linked to sulfate-reduction, methanogenesis, and hydrocarbon-degradation. The Linear discriminant analysis effect size revealed habitat-specific bioindicators according to the QR risk classification: (a) JTB255 marine benthic group (low risk); (b) Bacillus (moderate risk); and (c) sulfatereduction bacteria (high risk). Overall, the microbiota structure validated the QR risk classification, revealing both useful and efficient for monitoring the sediment quality status and risk of coastal sediments.
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Dates et versions

hal-04141906 , version 1 (26-06-2023)

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  • HAL Id : hal-04141906 , version 1

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Angelo Carvalho, Cristiana Cravo-Laureau, Vanessa Moreira, Alice Baldy, Vicente Murilo, et al.. Microbial indicators and Quality Ratio index for risk assessment in oil contaminated sediments of tropical coast. 3rd International Conference in Microbial Ecotoxicology (EcotoxicoMic 2022), Nov 2022, Montpellier, France. ⟨hal-04141906⟩
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