nm 22 uu 4500 fdr_mods_00000359 10.57892/100-359 doi fdr_mods_00000359 ger DE-601 rda eng 2026-05-05 2026-05-05 500 sdnb Freiberg, Jan-Frederik Author aut Research data for: Halocline boundary layer restricts the vertical distribution of the box jellyfish Tripedalia cystophora Freiberg, Jan-Frederik;Röhrdanz, Niels;Kohlstedt, Hermann;Bielecki, Jan (2026-05-05) 2026-05-05 data set xxx rdacontent Computermedien c rdamedia Online-Ressource cr rdacarrier embargo until 2026-05-15 Haloclines – sharp salinity gradients frequently formed after heavy rainfalls in coastal habitats – can act as barriers for weakly swimming plankton, but their biomechanical constraints on relatively adept swimmers, such as cubozoan jellyfish, remain unexplored. We examined the vertical distribution of Tripedalia cystophora before and after establishing an artificial halocline (35→22 PSU) in an experimental swimming arena. After halocline formation, animals repeatedly entered the gradient layer but did not ascend beyond its upper boundary, despite repeated upward trajectories towards the gradient layer, indicating no obvious avoidance response. A hydrodynamic model supported these observations, demonstrating that stratification drag markedly increases thrust dissipation. Thus, centimetre-scale haloclines impose physical constraints that prevent T. cystophora from accessing surface waters through reduced effective upward momentum, rather than through behavioural change. Because the underlying hydrodynamic principles are general, we propose a stratification hypothesis to explain how sharp density gradients shape the vertical distribution of some aquatic animals. database Röhrdanz, Niels Author aut Kohlstedt, Hermann Author aut Bielecki, Jan Author aut Faculties Faculty of Engineering host institution his https://opendata.uni-kiel.de/receive/fdr_mods_00000359 object in context https://opendata.uni-kiel.de/servlets/MCRFileNodeServlet/fdr_derivate_00000352/Repository.7z raw object https://opendata.uni-kiel.de/rsc/thumbnail/fdr_mods_00000359.png preview https://opendata.uni-kiel.de/receive/fdr_mods_00000359 uri