Mechanisms shaping size structure and functional diversity of phytoplankton communities in the ocean.
Mechanisms shaping size structure and functional diversity of phytoplankton communities in the ocean.
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DOI：
10.1038/srep08918
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发表时间：
2015-03-09
影响因子：
4.6
通讯作者：
Merico A
中科院分区：
文献类型：
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作者：
Acevedo-Trejos E;Brandt G;Bruggeman J;Merico A
浮游植物群落组成的调节因子在水生食物网的构建中起着至关重要的作用。然而，浮游植物群落中细胞大小组成差异的生物地理机制尚缺乏共识。在这里，我们使用一个基于特征的模型来解开大西洋两个截然不同地区的这些机制。在我们的模型中，浮游植物群落可以基于细胞大小与(1)营养摄取、(2)浮游动物放牧和(3)浮游植物下沉之间关系的权衡而自我组装。放牧“推动”群落向更大的细胞尺寸发展，而营养吸收和下沉“拉动”群落向更小的细胞尺寸发展。我们发现，热带稳定的环境条件强有力地平衡了这些力量，导致持续的小细胞尺寸和减少的尺寸多样性。相比之下，温带地区的季节性导致群落通过物种组成的变化定期重组，平均而言，比热带地区表现出更大的细胞大小和更高的大小多样性。我们的研究结果提高了环境变异性作为海洋浮游生物群落关键结构机制的重要性，并呼吁重新评估目前对浮游植物多样性格局跨纬度梯度的理解。
The factors regulating phytoplankton community composition play a crucial role in structuring aquatic food webs. However, consensus is still lacking about the mechanisms underlying the observed biogeographical differences in cell size composition of phytoplankton communities. Here we use a trait-based model to disentangle these mechanisms in two contrasting regions of the Atlantic Ocean. In our model, the phytoplankton community can self-assemble based on a trade-off emerging from relationships between cell size and (1) nutrient uptake, (2) zooplankton grazing, and (3) phytoplankton sinking. Grazing ‘pushes’ the community towards larger cell sizes, whereas nutrient uptake and sinking ‘pull’ the community towards smaller cell sizes. We find that the stable environmental conditions of the tropics strongly balance these forces leading to persistently small cell sizes and reduced size diversity. In contrast, the seasonality of the temperate region causes the community to regularly reorganize via shifts in species composition and to exhibit, on average, bigger cell sizes and higher size diversity than in the tropics. Our results raise the importance of environmental variability as a key structuring mechanism of plankton communities in the ocean and call for a reassessment of the current understanding of phytoplankton diversity patterns across latitudinal gradients.