"Large, filamentous nitrogen-fixing cyanobacteria (Trichodesmium spp., Nodularia spumigena and Aphanizomenon spp.) play an important role for primary production, input of nitrogen, and the microbial food webs in the ocean, in brackish waters (e.g. the Baltic Sea) and in lakes. Gas vesicles within filaments make these cyanobacteria positively buoyant to reach high light intensities in surface wate ...