Microbial diversity associated with copepods in the North Atlantic subtropical gyre

To characterize microscale spatial heterogeneity, microbial community composition of microzooplankton, primarily small copepods, was investigated in comparison to bacterioplankton in surrounding seawater from the oligotrophic open ocean. Zooplankton individuals were collected at or above the deep chlorophyll maximum in the North Atlantic Subtropical Gyre, and the diversity of microbial communities was investigated using 16S rRNA gene amplicon pyrosequencing targeting the V5-V9 region. Zooplankton studied included the copepods Undinula vulgaris, Pleuromamma spp., Sapphirina metalina, Pseudocalanus spp., and Tigriopus sp., and an amphipod, Phrosina semilunata. High -diversity was observed among samples, with zooplankton taxa-specific bacterial communities distinct from the communities in the surrounding seawater. The taxonomic composition of the microbial communities suggests both external and internal associations are present. Copepod association is a unique microbial niche that may play a role in biogeochemical cycling in the oligotrophic open ocean.