Impacts of multiple contamination of trace metal elements on the microbial communities in a highly anthropized coastal environnement : the Toulon bay ; Impacts de la contamination multiple en éléments traces métalliques sur les communautés microbiennes dans un environnement côtier fortement anthropisé : la rade de Toulon

Toulon Bay is a highly anthropized coastal ecosystem that present multiple trace metal contamination gradients, and was considered as a model system. The coupling of field campaigns and laboratory experiments were used to study the impact of trace metal contamination on bath planktonic and biofilm microbial communities. Chemical analyses, flux cytometry, and metabarcoding were used to study several characteristics of communities, as abundance and taxonomie diversity in response to trace metal contamination in the Toulon Bay. Then, bath ultraphytoplankton and bacterioplankton showed strong spatial patterns along the trace metal contamination gradients. Laboratory experiments showed that trace metals played an important raie on bath abundance and diversity patterns of ultraplanktonic communities, by bath potential direct (toxicity) and indirect (phytoplankton-bacterioplankton interactions). Conversely to planktonic communities, trace metal contamination had limited impact on microbial biofilm community. ln contrast, microbial biofilm community seemed to be influenced by surrounding sediments, and by potential colonizer taxa from benthic compartment resuspended du ring sediment resuspension events. ln conclusion, trace metals seemed to have impacts on all the microbial communities of Toulon Bay, with variations of influence depending on the compartment. ; La rade de Toulon est un écosystème côtier fortement anthropisé qui présente un gradient multiple de contamination en éléments traces métalliques, qui en fait un site atelier remarquable. Le couplage des campagnes de terrain et des expérimentations en laboratoire a permis d'étudier l'impact de la contamination métallique sur les communautés microbiennes planctoniques et en biofilm. L'utilisation de la chimie analytique, de la cytométrie en flux et du métabarcoding a permis d'étudier plusieurs aspects des communautés, comme l'abondance et la diversité taxonomique en réponse à la contamination métallique dans la rade de Toulon. Ainsi, les communautés ...