Methane is a relevant greenhouse gas that contributes to global warming. One possible methane sink is the metabolization by methanotrophic bacteria. These bacteria are able to use methane as sole carbon source and can be found in a broad variety of environments, such as soil, water and seafloor sediments. This study addresses the differences between methanotrophic communities in seafloor sediment samples and the community of artificial grown biofilms. This work was a cooperation of the Georg-August-University Göttingen and the Alfred Wegener Institute. The collection of data was done at the German offshore island Heligoland. Sediment samples were taken at the northern beach of the island along a transect from dunes to the intertidal zone. Moreover, growth of potential methanotrophic biofilms was implemented in Heligoland regarding different salt conditions. Therefore, biofilms from seawater as well as freshwater were cultivated and compared. In the freshwater experiment, the salinity was increased to determine potential changes within the biofilm community. Further analyses, such as Illumina sequencing, creation of a bioinformatic pipeline and electron microscopy of biofilm samples were performed at the university of Göttingen. This Master thesis gives an insight into the differences of methanotrophic communities in a relatively natural habitat and compares them to artificial biofilms. Furthermore, the study provides new observations regarding possible influences of climate change on marine methanotrophic communities and thus, on the global methane budget.