Basin-scale variability in phytoplankton size-abundance spectra across the Atlantic Ocean
Basin-scale variability in phytoplankton size-abundance spectra across the Atlantic Ocean
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DOI：
10.1016/j.pocean.2023.103104
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发表时间：
2023-08
影响因子：
4.1
通讯作者：
Cristina González-García;S. Agustí;J. Aiken;A. Bertrand;Gabriel Bittencourt Farias;A. Bode;C. Carré;Rafael Gonçalves‐Araujo;D. Harbour;M. Huete-Ortega;Pedro A.M.C. Melo;E. Moreno-Ostos;Andrew P. Rees;Jaime Rodríguez;Sonia da Silva;M. Zubkov;E. Marañón
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作者：
Cristina González-García;S. Agustí;J. Aiken;A. Bertrand;Gabriel Bittencourt Farias;A. Bode;C. Carré;Rafael Gonçalves‐Araujo;D. Harbour;M. Huete-Ortega;Pedro A.M.C. Melo;E. Moreno-Ostos;Andrew P. Rees;Jaime Rodríguez;Sonia da Silva;M. Zubkov;E. Marañón
浮游植物的大小结构是浮游生态系统营养结构和生物地球化学功能的主要决定因素，可以用大小-丰度谱(SAS)的斜率来描述。以前的观察性研究报告了浮游植物SAS坡度的时空变化，重点是特定的开阔海洋或沿海环境。因此，浮游植物SAS坡度的总体变异性仍然没有在生物量和生产力的广泛范围内进行调查，包括少营养的开阔海域和多产的沿海水域。在这里，我们提供了跨大西洋浮游植物生物量和SAS坡度的盆地尺度变异性的多航次概述，涵盖了50°N-50°S纬度范围内的海岸、陆架和海洋环境。我们发现，细胞大小和丰度之间的反向关系在所研究的地区普遍存在，即使在生产力高的沿海水域也是如此。在海洋区域，北极线深度、浮游植物生物量与SAS斜率之间的关系呈现一致的纬度格局。表层和真光层底部的SAS斜率之间存在很强的协变性，表明浮游植物大小结构的地理变化压倒了垂直变化。资源供应的增加、浮游植物生物量的增加和陡峭的SAS坡度逐渐变小之间存在着盆地规模的关系，这反映出大型细胞在更多产的水域中的重要性日益增加。然而，生态系统生产力与SAS斜率和群落平均细胞大小之间的关系是饱和的，这意味着较大的细胞对生态系统生产力的贡献没有持续增加的趋势。在中度和高度富营养化水域中都发现了类似的浮游植物大小结构，生物量优势为2-20μm大小类别。我们的结果为检验基于大小的浮游生物模型的预测和评估未来大西洋沿海和海洋区域浮游植物大小结构的气候相关变化提供了一个观测基准。
Phytoplankton size structure, a major determinant of trophic structure and biogeochemical functioning in pelagic ecosystems, can be described by the slope of the size-abundance spectrum (SAS). Previous observational studies reporting spatio-temporal changes in phytoplankton SAS slope have focused on particular open-ocean or coastal environments. Therefore, the overall variability in phytoplankton SAS slope still has not been investigated over wide ranges of biomass and productivity including both oligotrophic open-ocean regions and productive coastal waters. Here we present a multi-cruise overview of the basin-scale variability in phytoplankton biomass and SAS slope across the Atlantic Ocean, covering coastal, shelf, and oceanic environments over the 50°N-50°S latitude range. We find the inverse relationship between cell size and abundance to be pervasive across the studied regions, even in highly productive coastal waters. In oceanic regions, consistent latitudinal patterns are observed in the relationship between nutricline depth, phytoplankton biomass and SAS slope. There is a strong degree of covariation between SAS slope at the surface and at the base of the euphotic layer, indicating that geographical changes in phytoplankton size structure override vertical variability. A basin-scale relationship exists between increasing resource supply, enhanced phytoplankton biomass, and progressively less steep SAS slopes, reflecting increasing importance of large cells in more productive waters. However, the relationship between ecosystem productivity and both SAS slope and mean community cell size is saturating, which means there is no continuous trend towards ever increasing contribution by larger cells. Similar phytoplankton size structures, with a biomass dominance by the 2–20 μm size class, are found in both moderately and highly eutrophic waters. Our results provide an observational benchmark for testing the predictions of size-based plankton models and for assessing future, climate-related shifts in phytoplankton size structure in both coastal and oceanic regions of the Atlantic Ocean.