Mesoscale structure of neuston assemblages across the southern Indian Ocean subtropical gyre

Despite concern around plastic pollution in subtropical gyres, our understanding of the biological component neustonic layer (upper 20 cm ocean) these areas is poor. Here we investigate neuston (excluding copepods) assemblages across Southern Indian Subtropical Gyre using triplicate samples collected by manta-trawls from 28 stations along a transect at latitude S during June/July 2015. The vertical structure water column each station was assessed CTD. With exception siphonophores, all non-copepod were identified to morphospecies. Assemblages dominated ostracods, mysids, larval chaetognaths and siphonophores. majority specimens comprised facultative neuston, which more common night than day. Neuston east quite distinct balance samples, their distribution reflected that warm, low salinity associated with Indonesian Throughflow. Two anticyclonic eddies had been documented time survey between 70 85° E, this area assemblage generally abundance. key environmental factors linked longitude – salinity, fluorescence temperature 200 m, emphasising interaction Throughflow Water South Equatorial Current, eddy-related process settlement meroplankton. study highlights value morphospecies studies plankton assemblages.