Protist diversity in the Okinawa Trough and Kuroshio Current

The Okinawa Trough, a deep basin within the East China Sea, represents an ideal location to investigate the effects of water mass composition and proximity to hydrothermal vents on protist diversity. Despite global sampling efforts, protist biogeography is still a complicated issue and endemism versus cosmopolitanism remain as competing theories. This study compared protist diversity and community composition in water samples collected at 4 depths--surface, subsurface chlorophyll maximum, mid and bottom--from 14 stations in the Okinawa Trough, including several hydrothermal vent sites. Protist community composition in water samples varied primarily by sampling depth, but was also influenced by water mass composition and hydrothermal activity. Sequences that were significantly more abundant at hydrothermal vents matched reference sequences from myriad other locations throughout the global ocean, supporting cosmopolitanism in marine protists.