This comprehensive and interdisciplinary research cruise will assess the hydrographic and ecological situation of the central Sargasso Sea pelagic community, its key components and major trophic pathways. Special focus will be given to the early life history stages (eggs and leptocephali) of the two Atlantic freshwater eel species of the genus Anguilla in their presumed spawning grounds to elucidate potential causes for the catastrophic decline of the commercially important European eel stock. The huge Atlantic garbage patch in this area will be analysed for interactions between microbial processes and microplastic particles, which may also impact the fitness of eel larvae. In addition, the apparent decline of the habitat-shaping pelagic Sargassum macroalgae will be investigated via an ecophysiological approach to identify stressors in relation to climate change (e.g. temperature, UV).