Experiments have revealed much about top‐down and bottom‐up control in ecosystems, but manipulative experiments are limited in spatial and temporal scale. To obtain a more nuanced understanding of trophic control over large scales, we explored long‐term time‐series data from 13 globally distributed lakes and used empirical dynamic modelling to quantify interaction strengths between zooplankton and phytoplankton over time within and across lakes. Across all lakes, top‐down effects were associated with nutrients, switching from negative in mesotrophic lakes to positive in oligotrophic lakes. This result suggests that zooplankton nutrient recycling exceeds grazing pressure in nutrient‐limited systems. Within individual lakes, results were consistent with a ‘seasonal reset’ hypothesis in which top‐down and bottom‐up interactions varied seasonally and were both strongest at the beginning of the growing season. Thus, trophic control is not static, but varies with abiotic conditions – dynamics that only become evident when observing changes over large spatial and temporal scales.

中文翻译：

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湖泊的营养控制随着季节和养分含量的变化而变化。

实验揭示了有关生态系统自上而下和自下而上的控制的许多内容，但是操纵性实验在空间和时间尺度上受到限制。为了获得对大尺度营养控制的更细致入微的理解，我们探索了来自13个全球分布的湖泊的长期时间序列数据，并使用经验动态模型来量化随时间推移湖泊内和湖泊之间浮游动物与浮游植物之间的相互作用强度。在所有湖泊中，自上而下的影响与养分有关，从中营养湖泊的负离子转换为贫营养湖泊的正离子。这一结果表明，浮游动物的养分循环超过了养分限制系统中的放牧压力。在各个湖泊中，结果与“季节性重置”假设一致，在该假设中，自上而下和自下而上的交互作用随季节变化，并且在生长季节开始时最强。因此，营养控制不是静态的，而是随非生物条件的变化而变化–动态只有在观察大的时空尺度上的变化时才变得明显。