Seychelles–Chagosthermocline ridge is one of the major upwelling area in the tropical Indian Ocean, where planktons are known to have large impacts on ocean ecosystem and biogeochemical cycles. Time series assessments of surface zooplankton abundance, biovolume, and community composition were carried out in the Indian Ocean during June 2014. In this paper, we explore the impact of phytoplankton size class biomass on trophic interaction in the thermocline ridge of the southwestern tropical Indian Ocean. Relatively, nitrate was a dominant contributor than the nitrite in the dissolved inorganic nitrogen pool. Size fractionated chlorophyll-a concentration clearly showed that the study area was a typical oligotrophic open ocean, in which picophytoplankton biomass was dominated, accounted for approximately 72% of total Chl a. We assumed that picophytoplankton biomass was most likely influenced by dissolved inorganic nutrients (chiefly nitrite), that showed a strong linear relationship with picophytoplankton biomass (${\mathit{r}}^2=0$.41). These results support the key role of nitrite is not only supplying and promoting the growth of smaller phytoplankton biomass, but also controls the structure of zooplankton communities. As a result surface waters were dominated by picophytoplankton biomass, in this condition result in zooplankton being dominated by Poecilostomatoida, constituting approximately 68% of the total zooplankton count. These organisms were widely distributed and occurred in large numbers and displayed a strong linear relationship with picophytoplankton biomass (${\mathit{r}}^2=0$.87). These empirical results suggest that abundance of poecilostomatoids presumably supports tertiary trophic levels, suggesting they might play a key role as carbon drivers in the vicinity of the thermocline ridge of the Indian Ocean.

塞舌尔-查戈斯温跃层海脊是热带印度洋主要的上升流区之一，已知浮游生物对海洋生态系统和生物地球化学循环有很大影响。2014 年 6 月在印度洋进行了地表浮游动物丰度、生物量和群落组成的时间序列评估。 在本文中，我们探讨了热带印度洋西南部温跃层中浮游植物大小类别生物量对营养相互作用的影响. 相对而言，硝酸盐是溶解无机氮库中亚硝酸盐的主要贡献者。大小分馏叶绿素-a浓度清楚地表明，研究区是典型的贫营养型开阔洋，其中以微型浮游植物生物量为主，约占叶绿素a总量的72%。. 我们假设微型浮游植物生物量最有可能受到溶解的无机养分（主要是亚硝酸盐）的影响，这与微型浮游植物生物量显示出很强的线性关系。${\mathit{r}}^2=0$.41）。这些结果支持亚硝酸盐的关键作用不仅是供应和促进较小浮游植物生物量的生长，而且还控制着浮游动物群落的结构。因此，地表水以微型浮游植物生物量为主，在这种情况下，浮游动物以 Poecilostomatoida 为主，约占浮游动物总数的 68%。这些生物分布广泛，数量众多，与微型浮游植物生物量显示出很强的线性关系。${\mathit{r}}^2=0$.87）。这些实证结果表明，大量的拟口蝽可能支持三级营养水平，表明它们可能在印度洋温跃层脊附近作为碳驱动器发挥关键作用。