Typology of Plankton Communities seen by In Situ Imaging, from the Epi to the Mesopelagic Layers of the Global Ocean
We studied the distribution of plankton communities and their relationship with their immediate environment by analysing a global data set of ~3000 vertical CTD profiles equipped with an Underwater Vision Profiler 5 (UVP5). This represents over 700 000 images of large mesozooplankton, colonies of phytoplankton, and marine snow. Multivariate statistical ordination and regression methods were used to describe patterns in community composition and their correlation with environmental variables in three layers of the upper kilometer of the ocean (epi-, upper-meso- and lower-meso-pelagic).
Three types of plankton communities emerged: Trichodesmium-dominated in the intertropical band, Copepoda-dominated at high latitudes, or Rhizaria-dominated elsewhere; the mesopelagic layers lacked Trichodesmium. The comparison between the distribution of these communities and a set of existing biogeographical partitions of the ocean suggested that the structure of plankton communities described above is mostly driven by basin-level environmental conditions rather than the conditions in the immediate vicinity of the sampling site.