. . . . . "Photosynth\u00E8se" . . . "Productivit\u00E9 primaire (biologie)" . "Infrastructures marines" . "L\u2019accroissement des pressions anthropiques sur les \u00E9cosyst\u00E8mes marins et c\u00F4tiers, en particulier en Manche, provoquent des modifications des habitats, des \u00E9cosyst\u00E8mes et des diff\u00E9rentes fonctions \u00E9cosyst\u00E9miques associ\u00E9es. La construction d\u2019ouvrages maritimes et c\u00F4tiers tels que les digues ou des ouvrages portuaires ainsi que l\u2019\u00E9mergence de plusieurs projets d\u2019implantation d\u2019\u00E9oliennes off-shore est en augmentation constante sur les c\u00F4tes de la Manche fran\u00E7aise. Avec ces diff\u00E9rents projets, la b\u00E9tonisation de certains habitats devient in\u00E9vitable, il est donc primordial d\u2019\u00E9valuer leurs impacts \u00E9cosyst\u00E9miques, et, si possible, de les limiter. Le projet MARINEFF est n\u00E9 dans ce contexte, il vise \u00E0 concilier d\u00E9veloppement humain et b\u00E9n\u00E9fice \u00E9cologique. Le d\u00E9veloppement de ces nombreuses infrastructures c\u00F4ti\u00E8res cr\u00E9e de nouveaux habitats. L\u2019objectif de ces travaux a \u00E9t\u00E9 d\u2019\u00E9valuer les processus de colonisation biologique \u00E0 diff\u00E9rentes \u00E9chelles ainsi que certaines fonctions \u00E9cologiques comme la production primaire sur diff\u00E9rents types d\u2019infrastructures marines en conditions contr\u00F4l\u00E9es et en situation in situ dans deux sites La Rade de Cherbourg et la baie de Seine. Les mesures de fluorescence modul\u00E9e (PAM) r\u00E9alis\u00E9es sur les diff\u00E9rents compartiments de producteurs primaires benthiques ont permis d\u2019\u00E9valuer la fonction de production primaire et son \u00E9volution en fonction des for\u00E7ages test\u00E9s ou observ\u00E9s. Une part importante de ce travail s\u2019est concentr\u00E9e sur l\u2019\u00E9tude du microphytobenthos de substrat dur, sa croissance, sa photobiologie en relation avec le type de substrat colonis\u00E9, sa structure de surface et l\u2019impact de diff\u00E9rents for\u00E7ages sur ces param\u00E8tres. A une plus grande \u00E9chelle, le d\u00E9veloppement des communaut\u00E9s benthiques a \u00E9galement \u00E9t\u00E9 caract\u00E9ris\u00E9 sur les deux sites et sur diff\u00E9rentes infrastructures. Des mesures de production primaire in situ associ\u00E9es \u00E0 des mesures de biodiversit\u00E9 et de PAM ont permis de d\u00E9crire les processus de colonisation d\u2019infrastructures artificielles et d\u2019\u00E9valuer leur efficacit\u00E9. Ces travaux apportent une nouvelle vision \u00E0 l\u2019\u00E9cologie benthique associ\u00E9e aux substrats durs artificiels et apportent des estimations fiables de l\u2019impact de ces structures sur l\u2019\u00E9cosyst\u00E8me." . "R\u00F4le de la colonnisation d'infrastructures marines sur la production et la biodiversit\u00E9 des \u00E9cosyst\u00E8mes c\u00F4tiers en Manche" . "Th\u00E8ses et \u00E9crits acad\u00E9miques" . "Plantes benthiques" . . . "R\u00F4le de la colonnisation d'infrastructures marines sur la production et la biodiversit\u00E9 des \u00E9cosyst\u00E8mes c\u00F4tiers en Manche" . . "Animaux benthiques" . . . . "Biodiversit\u00E9" . . "Marine infrastructure colonisation role on coastal ecosystem biodiversity and production in the English Channel" . . . "Production primaire" . . . . "Microalgues benthiques" . "Increasing anthropogenic pressures on marine and coastal ecosystems, particularly in the English Channel, are causing changes in habitats, ecosystems and the various associated ecosystem functions. The construction of marine and coastal structures such as dikes as well as the emergence of several projects to install offshore wind turbines is constantly increasing on the French coasts of the English Channel. With these different projects, the concretization of certain habitats becomes inevitable, so it is essential to assess their ecosystem impacts, and, if possible, to limit them. The MARINEFF project was born in this context, it aims to reconcile human development and ecological benefit. The development of these many coastal infrastructures can also make it possible to create new habitats. The objective of this PhD is to assess biological colonization processes at different scales as well as certain ecological functions such as the primary production on different types of marine infrastructures under controlled conditions and in situ situations on two site the Rade of Cherbourg and the Bay of Seine. Modulated fluorescence (PAM) measurements carried out on the different compartments of benthic primary producers made it possible to evaluate the primary production function and its evolution according to the forcing\u2019s tested or observed. An important part of this PhD focused on the study of hard substrate microphytobenthos, its growth, its photobiology in relation to the type of colonized substrate, its surface structure and the impact of different forcing\u2019s on these parameters. On a larger scale, the development of benthic communities has also been characterized for both sites and on different infrastructures. In situ primary production measurements combined with biodiversity and PAM assessment have made it possible to describe the colonization processes of artificial infrastructures and to assess their effectiveness. This work brings a new vision to the benthic ecology associated with artificial hard substrates and makes it possible to provide reliable estimates of the impact of these structures on the ecosystem." . . "Text" . "2021" . . . . . .