Ciliate volumes were estimated using appropriate geometric shapes (cone, ball, and cylinder). Tintinnid carbon biomass was estimated using the equation89 (link): where C (μg C L−1) is the carbon biomass, Vi (μm3) is the lorica volume. We used a conversion factor of carbon biomass for aloricate ciliates of 0.19 pg/μm390 (link). The average abundance and biomass of the water column were calculated following Yu et al.91 (link) and Wang et al.92 (link). We used the Margalef index (dMa)93 and Shannon index (H′)94 (link) to test tintinnid diversity indices in the day and night variations. Biogeographically, the tintinnid genera are mainly classified into two groups in the oceanic waters based on Dolan and Pierce95 : Cosmopolitan, species distributed widespread in the world ocean; Warm Water, species observed in both coastal systems and open waters throughout the world ocean, but absent from sub-polar and polar waters.
The dominance index (Y) of tintinnid species in one assemblage was calculated using formula96 : where Ni is the number of individuals of species i in all samples, fi is the occurrence frequency of species i in all samples and N is the total number of species. Species with Y ≥ 0.02 represented the dominant species in an assemblage.
Distributional data of sampling stations, ciliates and environmental parameters (Depth, temperature, salinity, and Chl a) were visualized by ODV (Ocean Data View, Version 5.0), Surfer (Version 13.0), OriginPro 2021 (Version 9.6), and Grapher (Version 12.0). Correlation analysis between environmental and biological variables (nonparametric-test, Independent t-test, Spearman’s rank analysis) were performed using SPSS (Version 16). The significance for grouping in the environment and ciliate community (aloricate ciliate and tintinnid) was tested by PERMANOVA analysis in PERMANOVA C of PRIMER 697 ,98 (link). The partial Mantel tests were performed between ciliate community and environmental factors in R4.1.1.
The dominance index (Y) of tintinnid species in one assemblage was calculated using formula96 : where Ni is the number of individuals of species i in all samples, fi is the occurrence frequency of species i in all samples and N is the total number of species. Species with Y ≥ 0.02 represented the dominant species in an assemblage.
Distributional data of sampling stations, ciliates and environmental parameters (Depth, temperature, salinity, and Chl a) were visualized by ODV (Ocean Data View, Version 5.0), Surfer (Version 13.0), OriginPro 2021 (Version 9.6), and Grapher (Version 12.0). Correlation analysis between environmental and biological variables (nonparametric-test, Independent t-test, Spearman’s rank analysis) were performed using SPSS (Version 16). The significance for grouping in the environment and ciliate community (aloricate ciliate and tintinnid) was tested by PERMANOVA analysis in PERMANOVA C of PRIMER 697 ,98 (link). The partial Mantel tests were performed between ciliate community and environmental factors in R4.1.1.
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