Murphy Grace E P, Romanuk Tamara N, Worm Boris
Department of Biology Dalhousie University Halifax NS Canada.
Ecol Evol. 2020 Feb 5;10(4):2170-2181. doi: 10.1002/ece3.6055. eCollection 2020 Feb.
Plankton communities account for at least half of global primary production and play a key role in the global carbon cycle. Warming and acidification may alter the interaction chains in these communities from the bottom and top of the food web. Yet, the relative importance of these potentially complex interactions has not yet been quantified. Here, we examine the isolated and combined effects of warming, acidification, and reductions in phytoplankton and predator abundances in a series of factorial experiments. We find that warming directly impacts the top of the food web, but that the intermediate trophic groups are more strongly influenced by indirect effects mediated by altered top-down interactions. Direct manipulations of predator and phytoplankton abundance reveal similar strong top-down interactions following top predator decline. A meta-analysis of published experiments further supports the conclusion that warming has stronger direct impacts on the top and bottom of the food web rather than the intermediate trophic groups, with important differences between freshwater and marine plankton communities. Our results reveal that the trophic effect of warming cascading down from the top of the plankton food web is a powerful agent of global change.
浮游生物群落至少占全球初级生产的一半，并在全球碳循环中发挥关键作用。变暖和酸化可能会从食物网的底部和顶部改变这些群落中的相互作用链。然而，这些潜在复杂相互作用的相对重要性尚未得到量化。在这里，我们在一系列析因实验中研究了变暖和酸化以及浮游植物和捕食者丰度降低的单独和综合影响。我们发现，变暖直接影响食物网的顶部，但中间营养级群体受自上而下相互作用改变介导的间接影响更大。对捕食者和浮游植物丰度的直接操纵揭示了顶级捕食者数量下降后类似的强烈自上而下的相互作用。对已发表实验的荟萃分析进一步支持了这一结论，即变暖对食物网的顶部和底部有更强的直接影响，而不是中间营养级群体，淡水和海洋浮游生物群落之间存在重要差异。我们的结果表明，从浮游生物食物网顶部 cascading down 的变暖的营养效应是全球变化的一个强大因素。 （注：“cascading down”此处可能有误，推测原文可能是“cascading”，可译为“级联” ，整句为从浮游生物食物网顶部级联下来的变暖的营养效应）
