Vertical distribution of planktonic ciliates in the oceanic and slope areas of the western Pacific Ocean

摘要

Ciliates are important grazers in the planktonic food web, and spatial distribution information is the key to understanding their function. However, our understanding of their vertical distribution in the euphotic zone of oceanic waters is limited. In this study, we investigated the vertical distribution of ciliates in the western Pacific Ocean and the northern South China Sea. The ciliates showed a bimodal distribution, with abundance peaks in surface waters and the deep chlorophyll maximum (DCM) in the western Pacific, but a single surface peak in the northern South China Sea slope. At stations influenced by shelf water, the surface abundance was much greater than in slope waters. Within the ciliates, the vertical distribution of tintinnid species groups I and V had higher abundances overall and showed surface and DCM peaks, respectively. We speculate that aloricate ciliates might also have surface peak and DCM peak groups. The overall vertical distribution patterns showed that the planktonic food web may function differently within the surface waters and the DCM.