“…Dispersal is important in the emergence and maintenance of plankton biogeography ( 23 , 25 , 39 , 46 , 47 ). In this study, sampling sites from the South China Sea, across the Gulf of Bengal, to the northern Arabian Sea might be connected by ocean currents, such as the winter western Indian Coastal Current, the Northeast Indian Monsoon Current, and the surface circulation of the South China Sea ( 48 – 50 ). Because marine plankton bacteria are unable to swim against currents, their (plankton bacteria) biogeography is shaped by current systems, as demonstrated by a recent study that analyzed the metagenomes of plankton communities that were sampled across global oceans during the Tara Oceans expedition ( 47 ).…”