Phytoplankton elemental composition regulates the efficiency of energy and material transfer in the interface between phytoplankton and their consumers. The ratio of particulate organic carbon to particulate organic nitrogen (POC:PON) shows considerable regional deviations from the canonical Redfield ratio in the global surface ocean. However, in certain oceanic regions such as the northwest Pacific Ocean (NWPO) POC:PON distribution and its ecological significance remain uncertain. We investigated surface ocean POC:PON distributions at 66 stations in the NWPO, and quantified the correlations between POC:PON and multiple biotic and abiotic factors including sea surface temperature (SST), nutrient concentrations and multiple lipid biomarkers (fatty acids and sterols), by combining correlation analyses and generalized additive models. POC:PON (range: 3.53–14.18 M ratios; median: 6.89) was overall higher in the (sub)tropical biome than that in the high-latitude biome. In the entire study region, SST, nutrient concentration and lipid-derived phytoplankton community structure explained 41 %, 33 % and 26 % of the variance in POC:PON, respectively, while the respective importance of each factor differed between the (sub)tropical and high-latitude biomes. Furthermore, we calculated the percentage of primary production consumed by herbivores (PPC; 54–156 %), showing a higher mean value (117 %) in the high-latitude biome and a lower one (92 %) in the (sub)tropical biome. The spatial distribution pattern of PPC can be attributed to multiple factors, with PPC correlating negatively with SST and positively with lipid-based indicators of phytoplankton food quality and POC concentrations. The increase in SST may be associated with a reduced nitrogen content, resulting in lower PPC in the (sub)tropical biome. This study highlights the significance of SST and elemental and biochemical composition of phytoplankton in regulating the transfer of organic carbon to herbivores in the NWPO.

中文翻译：

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C：N 化学计量与西北太平洋生态系统中有机碳的归宿


浮游植物元素组成调节浮游植物与其消费者之间界面中能量和物质转移的效率。颗粒有机碳与颗粒有机氮的比率 （POC：PON） 与全球表层海洋中的典型雷德菲尔德比率存在相当大的区域偏差。然而，在某些海洋区域，例如西北太平洋 （NWPO），POC：PON分布及其生态意义仍不确定。我们研究了 NWPO 中 66 个站点的表层海洋 POC：PON 分布，并通过结合相关性分析和广义加性模型量化了 POC：PON 与多种生物和非生物因素之间的相关性，包括海表温度 （SST）、营养浓度和多种脂质生物标志物（脂肪酸和甾醇）。POC：PON（范围：3.53–14.18 M 比率;中位数：6.89）在（亚）热带生物群落中总体上高于高纬度生物群落。在整个研究区域，SST、营养浓度和脂质衍生的浮游植物群落结构分别解释了 POC：PON 的 41 % 、 33 % 和 26 % 的方差，而每个因素的各自重要性在（亚）热带和高纬度生物群落之间有所不同。此外，我们计算了食草动物消耗的初级生产百分比 （PPC;54-156 %），在高纬度生物群落中显示出较高的平均值 （117 %），在（亚）热带生物群落中具有较低的平均值 （92 %）。PPC 的空间分布模式可归因于多种因素，其中 PPC 与 SST 呈负相关，与浮游植物食物质量和 POC 浓度的脂质指标呈正相关。 SST 的增加可能与氮含量降低有关，从而导致（亚）热带生物群落中的 PPC 降低。本研究强调了 SST 以及浮游植物的元素和生化组成在调节 NWPO 中有机碳向食草动物转移的重要性。