Temperature appears to be the best predictor of species composition of planktonic foraminifera communities, making it possible to use their fossil assemblages to reconstruct sea surface temperature (SST) variation in the past. However, the role of other environmental factors potentially modulating the spatial and vertical distribution of planktonic foraminifera species is poorly understood. This is especially relevant for environmental factors affecting the subsurface habitat. If such factors play a role, changes in the abundance of subsurface-dwelling species may not solely reflect SST variation. In order to constrain the effect of subsurface parameters on species composition, we here characterize the vertical distribution of living planktonic foraminifera community across an east–west transect through the subtropical South Atlantic Ocean, where SST variability was small, but the subsurface water mass structure changed dramatically. Four planktonic foraminifera communities could be identified across the top 700 m of the transect. Gyre and Agulhas Leakage surface faunas were predominantly composed of Globigerinoides ruber, Globigerinoides tenellus, Trilobatus sacculifer, Globoturborotalita rubescens, Globigerinella calida, Tenuitella iota, and Globigerinita glutinata, and these only differed in terms of relative abundances (community composition). Upwelling fauna was dominated by Neogloboquadrina pachyderma, Neogloboquadrina incompta, Globorotalia crassaformis, and Globorotalia inflata. Thermocline fauna was dominated by Tenuitella fleisheri, Globorotalia truncatulinoides, and Globorotalia scitula in the west and by G. scitula only in the east. The largest part of the standing stock was consistently found in the surface layer, but SST was not the main predictor of species composition either for the depth-integrated fauna across the stations or at individual depth layers. Instead, we identified a pattern of vertical stacking of different parameters controlling species composition, reflecting different aspects of the pelagic habitat. Whereas productivity appears to dominate in the mixed layer (0–60 m), physical properties (temperature, salinity) become important at intermediate depths and in the subsurface, a complex combination of factors including oxygen concentration is required to explain the assemblage composition. These results indicate that the seemingly straightforward relationship between assemblage composition and SST in sedimentary assemblages reflects vertically and seasonally integrated processes that are only indirectly linked to SST. It also implies that fossil assemblages of planktonic foraminifera should also contain a signature of subsurface processes, which could be used for paleoceanographic reconstructions.

中文翻译：

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亚热带南大西洋浮游有孔虫的分布：控制因素的深度层次

温度似乎是浮游有孔虫群落物种组成的最佳预测指标，过去可以利用它们的化石组合来重建海面温度（SST）变化。但是，其他环境因素可能调节浮游有孔虫物种的空间和垂直分布的作用知之甚少。这对于影响地下生境的环境因素尤其重要。如果这些因素起作用，那么地下居住物种的丰度变化可能不仅仅反映SST的变化。为了限制地下参数对物种组成的影响，我们在这里描述了通过亚热带南大西洋东西向横断面的浮游有孔虫群落的垂直分布，SST变异较小，但地下水团结构发生了巨大变化。在前700名中可以找到四个浮游有孔虫群落 横断面的m。Gyre和Agulhas渗漏表面动物主要由Globigerinoides ruber，Globigerinoides tenellus，Trilobatus sacculifer，Globoturborotalita rubescens，Globigerinella calida，Tenuitella iota和Globigerinita glutinata组成，它们的相对丰度差异很大。涌动物被支配Neogloboquadrina pachyderma，Neogloboquadrina incompta，Globorotalia crassaformis和Globorotalia胀。跃层动物区系由西部的特奈特氏菌（Tenuitella fleisheri），球果总纲（Globorotalia truncatulinoides）和球果总纲（Globorotalia scitula）在东部仅受G. scitula的影响。始终在表层中找到最大数量的站立种群，但无论是跨站的深度整合动物群还是在各个深度层，SST都不是物种组成的主要预测指标。相反，我们确定了控制物种组成的不同参数的垂直堆叠模式，反映了中上层生境的不同方面。而在混合层（0-60  m），物理特性（温度，盐度）在中间深度和地下非常重要，需要复杂的因素组合（包括氧气浓度）来解释组合物的组成。这些结果表明，沉积物组合中组合物成分与SST之间看似直接的关系反映了垂直和季节性整合过程，这些过程仅与SST间接相关。这也意味着浮游有孔虫的化石组合还应该包含地下过程的特征，这些特征可以用于古海洋重建。