Vertical Distribution Of Planktonic Ciliates In Tropical Western Pacific And The Slope Of Northern South China Sea

Marine planktonic ciliates are unicellular, eukaryotic protists(size range of 10-200 μm) and ubiquitous in various marine habitats. They are belong to ProtozoaCiliophora-Oligotrichea-Oligotrichina and Tintinnina, including aloricate ciliates and tintinnids. Microzooplankton is a key trophic group in pelagic ecosystems, as these organisms consume most of the primary production. As the dominant component of the microzooplankton, Planktonic ciliate is a key medium through microbial food web to classical food chain, which play an important role in material circulation and energy flow of marine ecosystem.Vertical distribution of planktonic ciliates in different sea regions are limited. In this study, we collect some relevant information about vertical distribution of planktonic ciliates in different sea regions, and the abundance, biomass, spacial and full-depth vertical distribution of planktonic ciliates, size-fraction of the aloricate ciliates, species richness of tintinnids in the Yap seamount and western Pacific and the slope of the northern South China Sea area. We have a preliminary study about the correlation between the ciliates abundance and the Chl a in vivo fluorescence in different vertical distribution patterns.Vertical distribution of planktonic ciliates in tropical western pacific of Philippine sea region and the Yap seamount areaThe full-depth abundance and biomass and community structure of planktonicciliates were investigated in the Yap seamount area and along a transect from south Taiwan to Yap seamount in western Pacific from December 2014 to January 2015.Abundance and biomass ranged from 0 to 635 ind/L, and from 0 to 1.53 μg C/L,respectively. High abundance and biomass were found in the upper 200 m. The abundance of tintinnid ranged from 0 to 45 ind/L, and occupied 0-14.62% of the total ciliates abundance in all stations of the layers in 0-200 m. The size-fraction of the aloricate ciliates which above 50 μm were most appeared in the surface layer. The vertical distribution of planktonic ciliates abundance showed “Bimodal-peak” pattern in this area, and there have a very significant correlation between the ciliates abundance and the Chl a in vivo fluorescence. Ciliates abundance was high in the surface and the deep chlorophyll maximum(DCM) layers. This vertical distribution pattern was different from previous studies. In taxonomy, 76 tintinnid species of 33 genera were identified. Cosmopolitan(37 tintinnid species of 13 genera) and Warm water(31 tintinnid species of 14 genera) were the main pattern in this area and which occupied 48.7% and 40.8% in total tintinnids, respectively. The dominant species in the Yap Seamount were Steenstrupiella gracilis, Eutintinnus lusus-undae, Eutintinnus tubulosus, Undella turgida and in the western pacific of Philippine sea region were Steenstrupiella gracilis, Eutintinnus haslae, Dadayiella ganymedes, Salpingella acμminata. Some species occurred in waters shallower than 100 m(e.g. Codonella tropica, Poroecus apiculatus) while some occurred in waters deeper than 100 m(e.g.Codonellopsis parva, Parundella lohmanni). Therefore, the depth 100 m is where the tintinnid species composition changed.Vertical distribution of planktonic ciliates in slope of northern South China SeaOceanic water and continental water meet in the slope of the northern South China Sea. Therefore, biological characteristic of planktonic ciliates should be different in slope and oceanic area. Planktonic ciliates abundance in the continental waters showed “Surface-peak” or “Subsurface-peak” pattern, independent from the deep chlorophyll a maximum layer(DCM) which is at deeper depth. We inspected the vertical distribution of planktonic ciliates in shelf-slope waters of northern south China Sea in October, 2014 and June, 2015, respectively. Abundance and biomass of ciliates ranged from 0 to 1353 ind/L, and from 0 to 2.36 μg C/L, respectively. High abundance and biomass were found in the upper 200 m. The size-fraction of the aloricate ciliates which above 50 μm were most appeared in the surface layer. The vertical distribution of planktonic ciliates abundance showed “surface-peak”,“subsurface-peak” and “bimodal-peak” pattern in this area, and the “bimodal-peak”pattern showed abundance peaks in surface water and DCM layer. The different vertical distribution patterns could be used to indicate the different origin of the water masses. In the patterns of bimodal-peak, there have a very significant correlation between the ciliates abundance and the Chl a in vivo fluorescence. 82 tintinnid species of 34 genera were identified. In autumn of this area, 63 tintinnid species of 29 genera were identified and the Cosmopolitan(28 tintinnid species of 11 genera) with Warm water(25 tintinnid species of 12 genera) were the main pattern in this season,which occupied 48.7% and 40.8% in total tintinnids, respectively. In summer of this area, 67 tintinnid species of 30 genera were identified and the Cosmopolitan(31tintinnid species of 12 genera) and Warm water(26 tintinnid species of 11 genera)also were the main pattern in this season and which occupied 48.7% and 40.8% in total tintinnids, respectively. The abundance of tintinnid ranged from 0 to 129 ind/L,and occupied 0-80% of the total ciliates abundance in all stations of the layers in 0- 200 m. The dominant species in autumn were Salpingella faurei, Eutintinnus apertus, Climacocylis scalaroides, Dadayiella ganymedes and in summer were Salpingella faurei, Dadayiella ganymedes, Salpingella acuminata, Proplectella parva.Tintinnid species like Leprotintinnus simplex, Codonaria oceanica, Tintinnopsis beroidea, T. lohmanni, T. radix, T. urnula, T. tubulosoides only occured in continental water, and the tintinnid species occured in oceanic water mostly were hyaline species.Some species occurred in waters shallower than 100 m(e.g. Amphorellopsis acuta,Climacocylis scalaroides) while some occurred in waters deeper than 100 m(e.g.Albatrossiella agassizi, Ormosella apsteini). Therefore, the depth 100 m is where the tintinnid species composition changed.