Small-sized cells contribute massively to the high diversity and distinct community structure of ciliates in mesopelagic waters of the northern South China Sea

Ciliates play key roles in the microbial loop of marine ecosystems. However, the partitioning of spatial, temporal, and environmental effects on ciliate distribution between environments remains largely unknown. An integrative approach was used to analyze ciliate communities by combining high-throughput cDNA sequencing and the quantitative protargol stain on seasonal samples collected along a transect from coastal to oceanic regions at depths ranging from the surface to 1000 m.