Abstract The Marquesas Islands, in the central South Pacific, is a region of enhanced phytoplankton enrichment visible from space and is a hotspot of endemism and biodiversity; however, it has been poorly studied. In situ physical-chemical-biological concomitant observations are almost non-existent and all located close to the main northern island, while ocean dynamics based on satellite observations and numerical modeling show contrasting north/south patterns within the archipelago. Thus, we took the opportunity of the Pakahi I te Moana cruise conducted in 2012 to collect hydrological and plankton samples and investigate biogeochemical spatial patterns, especially north/south, over the archipelago. These data provide the first description of the spatial and vertical distribution of physical, chemical and plankton characteristics over the entire Marquesas archipelago, and give a first hint to improve our understanding of this planktonic enrichment. The whole archipelago appeared to be a macronutrient-rich environment. Different patterns in the physical, chemical and biological vertical distributions were observed between the northern vs. southern part of the archipelago, and offshore vs. nearshore stations. Phytoplankton biomasses were higher in the north where stratification was weaker, compared to the south and higher close to the islands than offshore. Phytoplankton all over the archipelago was largely dominated by picophytoplankton; specifically, Prochlorococcus presented a more widespread distribution than previously thought and were present over a large range of nutrient concentrations. Copepods were always the most abundant taxa in the archipelago but showed higher mean relative abundances near the islands. The importance of suspension-feeding zooplankton in the northern islands coincided with the highest biomasses of phytoplankton with a predominance of nano- and micro-phytoplankton. This was consistent with a young community responding to nutrient enrichment by an increase of suspension-feeders animals and bottom-up effect on zooplankton. Opposite to this, small copepods were significantly less abundant in the northern offshore region and the dominance of carnivorous forms coincided with low phytoplankton biomass and strong dominance of picoplankton, suggesting a microbial grazing pathway and more mature communities.

中文翻译：

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南太平洋马克萨斯群岛内的浮游生物空间变异性

摘要 位于南太平洋中部的马克萨斯群岛是一个从太空可见的浮游植物丰富的地区，是地方性和生物多样性的热点地区；然而，对它的研究很少。原位物理-化学-生物伴随观测几乎不存在，并且都位于北部主要岛屿附近，而基于卫星观测和数值模拟的海洋动力学显示群岛内南北模式形成鲜明对比。因此，我们利用 2012 年进行的 Pakahi I te Moana 巡航的机会收集了水文和浮游生物样本，并调查了群岛上空的生物地球化学空间模式，尤其是北/南。这些数据提供了物理空间和垂直分布的第一个描述，整个马克萨斯群岛的化学和浮游生物特征，并提供第一个提示，以提高我们对这种浮游生物富集的理解。整个群岛似乎是一个富含大量营养素的环境。在群岛的北部和南部以及离岸和近岸站之间观察到物理、化学和生物垂直分布的不同模式。与南部相比，分层较弱的北部浮游植物生物量较高，靠近岛屿的地区高于离岸地区。整个群岛的浮游植物主要以微型浮游植物为主；具体来说，原绿球藻的分布比以前认为的更广泛，并且存在于很大的营养浓度范围内。桡足类一直是群岛中最丰富的分类群，但在岛屿附近显示出更高的平均相对丰度。悬浮摄食浮游动物在北部岛屿的重要性恰逢浮游植物的最高生物量与纳米和微型浮游植物的优势。这与年轻社区通过悬浮饲养动物的增加和对浮游动物的自下而上的影响对营养丰富的反应一致。与此相反，北部近海地区小型桡足类动物的数量明显较少，食肉动物的优势与浮游植物生物量低和微型浮游生物的优势相吻合，表明微生物放牧途径和更成熟的群落。悬浮摄食浮游动物在北部岛屿的重要性恰逢浮游植物的最高生物量与纳米和微型浮游植物的优势。这与年轻社区通过悬浮饲养动物的增加和对浮游动物的自下而上的影响对营养丰富的反应一致。与此相反，北部近海地区小型桡足类动物的数量明显较少，食肉动物的优势与浮游植物生物量低和微型浮游生物的优势相吻合，表明微生物放牧途径和更成熟的群落。悬浮摄食浮游动物在北部岛屿的重要性恰逢浮游植物的最高生物量与纳米和微型浮游植物的优势。这与年轻社区通过悬浮饲养动物的增加和对浮游动物的自下而上的影响对营养丰富的反应一致。与此相反，北部近海地区小型桡足类动物的数量明显较少，食肉动物的优势与浮游植物生物量低和微型浮游生物的优势相吻合，表明微生物放牧途径和更成熟的群落。这与年轻社区通过悬浮饲养动物的增加和对浮游动物的自下而上的影响对营养丰富的反应一致。与此相反，北部近海地区小型桡足类动物的数量明显较少，食肉动物的优势与浮游植物生物量低和微型浮游生物的优势相吻合，表明微生物放牧途径和更成熟的群落。这与年轻社区通过悬浮饲养动物的增加和对浮游动物的自下而上的影响对营养丰富的反应一致。与此相反，北部近海地区小型桡足类动物的数量明显较少，食肉动物的优势与浮游植物生物量低和微型浮游生物的优势相吻合，表明微生物放牧途径和更成熟的群落。