AIM: Nutrient subsidies support high primary productivity, increasing herbivore abundance and influencing their top‐down control of producers. Wind‐driven upwelling events deliver cold nutrient‐rich water to coastlines, supporting highly productive marine environments. Results from studies comparing ecological processes across upwelling regimes are mixed: some reveal weaker herbivory in upwelling regions, while others report a positive relationship between upwelling and herbivory. In this synthesis we examine the influence of upwelling on top‐down control of producers across the globe. LOCATION: Global; marine ecosystems. TIME PERIOD: 1978–2017. MAJOR TAXA STUDIED: Marine herbivores and algae. METHODS: We used data from herbivory studies focusing specifically on the influence of upwelling activity (upwelling studies), and a broader collection of herbivore exclusion studies dating back four decades. For the upwelling studies we compared herbivore effects between experiments replicated across sites for which upwelling conditions were described by the authors. Meanwhile, for the broader collection of experiments we used externally sourced oceanographic data to characterize upwelling activity, and examined how herbivory changed along a gradient of upwelling activity. RESULTS: Our results consistently reveal that upwelling weakens herbivore effects on producers. Herbivory was, on average, four times weaker in upwelling sites relative to sites under weak upwelling or downwelling regimes in studies that specifically examined upwelling. The analysis of the broader herbivory literature revealed a similar weakening influence of upwelling on herbivory; however, the effect size was smaller and varied across producer functional groups. MAIN CONCLUSIONS: Nutrient subsidies from upwelling events reduce top‐down control by herbivores in coastal ecosystems; however, the negative relationship between upwelling intensity and herbivory is likely the result of a combination of co‐occurring processes. First, increased primary production overwhelms consumption by herbivores. Second, cold water reduces herbivore metabolism and activity. Finally, surface currents associated with upwelling activity transport herbivore larvae offshore, decoupling secondary production from herbivory.

中文翻译：

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海洋上升流如何影响食草动物的全球荟萃分析

目标：营养补贴支持较高的初级生产力，增加食草动物的数量并影响他们对生产者的自上而下的控制。风驱动的上升流事件为海岸线提供富含营养的冷水，支持高产的海洋环境。比较不同上升流机制的生态过程的研究结果喜忧参半：一些揭示上升流区域的食草动物较弱，而另一些则报告上升流与食草动物之间存在正相关关系。在这个综合中，我们研究了上升流对全球生产者自上而下控制的影响。地点：全球；海洋生态系统。时间段：1978-2017。研究的主要类群：海洋食草动物和藻类。方法：我们使用来自食草研究的数据，特别关注上升流活动的影响（上升流研究），以及更广泛的可追溯到四年前的草食动物排斥研究。对于上升流研究，我们比较了在作者描述的上升流条件的地点重复的实验之间的食草动物效应。同时，对于更广泛的实验收集，我们使用外部来源的海洋学数据来表征上升流活动，并研究食草动物如何沿着上升流活动梯度发生变化。结果：我们的结果一致表明，上升流减弱了食草动物对生产者的影响。在专门检查上升流的研究中，相对于弱上升流或下降流制度下的站点，食草动物在上升流站点中平均弱四倍。对更广泛的食草文献的分析揭示了上升流对食草动物的类似减弱的影响；然而，效应量较小，且因生产者职能组而异。主要结论：来自上升流事件的营养补贴减少了沿海生态系统中食草动物自上而下的控制；然而，上升流强度和食草动物之间的负相关很可能是同时发生的过程组合的结果。首先，初级生产的增加超过了食草动物的消费。其次，冷水会降低食草动物的新陈代谢和活动。最后，与上升流活动相关的地表水流将食草动物幼虫运送到近海，将二次生产与食草动物脱钩。上升流强度和食草动物之间的负相关可能是同时发生的过程组合的结果。首先，初级生产的增加超过了食草动物的消费。其次，冷水会降低食草动物的新陈代谢和活动。最后，与上升流活动相关的地表水流将食草动物幼虫运送到近海，将二次生产与食草动物脱钩。上升流强度和食草动物之间的负相关可能是同时发生的过程组合的结果。首先，初级生产的增加超过了食草动物的消费。其次，冷水会降低食草动物的新陈代谢和活动。最后，与上升流活动相关的地表水流将食草动物幼虫运送到近海，将二次生产与食草动物脱钩。