This dataset is the base of the project, that investigates the biodiversity, community composition, and functional roles of carabid beetles across salinity gradients in the terrestrial marshlands of the Elbe Estuary. The overarching goal is to understand how carabid beetle assemblages contribute to ecosystem connectivity, functioning, and carbon cycling within these ecotonal systems. This research is part of the graduate school program “Biota-Mediated Effects on Carbon Cycling in Estuaries”.