Impacts of the Zhe-Min Coastal Current on the biogeographic pattern of microbial eukaryotic communities

Spatiotemporal Patterns in Diversity and Assembly Process of Marine Protist Communities of the Changjiang (Yangtze River) Plume and Its Adjacent Waters

“…All the factors mentioned previously could have an impact on protist grazing on picoplankton (i.e., HB and PEUK; Choi et al, 2012 ) and result in “bottom-up” controls on the PCCs ( Caron and Hutchins, 2012 ). Notably, the environmental factors explained a larger proportion of the community variation in our samples (78.52%, Figure 1C ), compared with previous studies ( Mo et al, 2018 ; Xu et al, 2020 ). However, more key factors (e.g., pH, irradiation, turbidity, and particulate organic matters) were not included and should be considered in the future study of the complex coastal area ( Choi et al, 2012 ).…”

“…Temperature is considered to be a main factor that drives the seasonal variation in temperate coastal area of Changjiang plume and its adjacent waters ( Lee and Chao, 2003 ). Salinity and nutrient play critical roles in shaping the PCCs in the estuarine-coastal area subjected to freshwater discharge ( Liu et al, 2018 ; Xu et al, 2020 ). An annual cycle of hypoxia observed in the Changjiang plume were coupled with anthropogenic nutrient loading and coastal eutrophication ( Zhu et al, 2011 ) and with changes in the region of stratification ( Wang et al, 2012 ), which may induce the growth of protists due to their tolerance of low O 2 levels ( Caron and Hutchins, 2012 ).…”

“…It appears that multiple water masses from varied directions meet in the shelf area and the whole current system becomes relatively weak as stated previously, thus inducing dispersal limitation of the protist communities ( Lee and Chao, 2003 ). In contrast, high connectivity in the coastal area due to strong current transportation could weaken the dispersal limitation and cause high dispersal ability ( Xu et al, 2020 ). Furthermore, correlations between the environmental factors and community decreased considerably from the surface to the bottom layer, thus the spatial factors displayed relatively more important role in the bottom layer.…”

“…Protists (single-celled eukaryotes) are significant components in global marine ecosystems with wide distributions and high biodiversity in multiple trophic modes, which play fundamental roles in numerous essential ecological and biogeochemical processes ( Adl et al, 2012 ; Caron et al, 2012 ; Fuhrman et al, 2015 ; Keeling and del Campo, 2017 ). With the application of high-throughput sequencing (HTS) combined with metabarcoding, many studies have investigated the diversity and biogeographic distributions of the protist community compositions (PCCs) under dynamic temporal scales and different habitats ( Massana et al, 2015 ; Marquardt et al, 2016 ; Pernice et al, 2016 ; Wu et al, 2016 ; Liu et al, 2017 ; Xue et al, 2018 ; Zhang W. J. et al, 2018 ; Xu et al, 2020 ). However, much fewer studies have focused on protist community compared with bacterial communities ( Keeling and del Campo, 2017 ).…”

“…Besides, previous studies reported high nutrient input and hypoxia of the Changjiang plume area that had impact on the microbial communities ( Guo et al, 2014 ; Liu et al, 2017 ; Zhou et al, 2020 ), which was affected strongly by anthropogenic activities compared with peripheral continental shelf area ( Li and Daler, 2004 ). Dispersal-related stochastic processes caused by current transportation could also play critical roles in regulating the microbial communities ( Xu et al, 2020 ). Thus, the hydrological conditions display highly different spatial and temporal patterns between the coastal areas of Changjiang plume and its adjacent shelf areas ( Yeh et al, 2015 ; Liu et al, 2017 ), which should affect community assembly of PCCs differently, but is so far understudied.…”