Trophic cascades and climate change are together reshaping an iconic kelp forest ecosystem after the loss of sea otters. A lethal combination It is well established that predators are essential for the structuring and maintenance of biotic communities. One of the first demonstrations of this importance came from studies of the importance of sea otters to the maintenance of kelp forests. Rasher et al. now show that the effects caused by the absence of this predator can be further exacerbated by climate warming. In North Pacific kelp forests, otter absence led to a decline of slow-growing calcareous algae through sea urchin herbivory, and this pattern was amplified by warming temperatures. Keystone predators are thus essential not only for trophic structure but also for mitigating the impacts of climate change. Science, this issue p. 1351 Predator loss and climate change are hallmarks of the Anthropocene yet their interactive effects are largely unknown. Here, we show that massive calcareous reefs, built slowly by the alga Clathromorphum nereostratum over centuries to millennia, are now declining because of the emerging interplay between these two processes. Such reefs, the structural base of Aleutian kelp forests, are rapidly eroding because of overgrazing by herbivores. Historical reconstructions and experiments reveal that overgrazing was initiated by the loss of sea otters, Enhydra lutris (which gave rise to herbivores capable of causing bioerosion), and then accelerated with ocean warming and acidification (which increased per capita lethal grazing by 34 to 60% compared with preindustrial times). Thus, keystone predators can mediate the ways in which climate effects emerge in nature and the pace with which they alter ecosystems.

中文翻译：

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关键捕食者控制亚北极海洋生态系统气候影响的途径和速度


海獭消失后，营养级联和气候变化共同重塑了标志性的海带森林生态系统。致命的组合 众所周知，捕食者对于生物群落的构建和维持至关重要。这种重要性的最早证明之一来自对海獭对海带森林维护重要性的研究。拉舍尔等人。现在表明，气候变暖可能会进一步加剧这种捕食者缺失所造成的影响。在北太平洋海带森林中，水獭的消失导致海胆食草生长缓慢的钙质藻类数量减少，而这种模式因气温升高而加剧。因此，关键捕食者不仅对于营养结构至关重要，而且对于减轻气候变化的影响也至关重要。科学，本期第 14 页。 1351 捕食者的消失和气候变化是人类世的标志，但它们的相互作用影响在很大程度上是未知的。在这里，我们发现，由藻类 Clathromorphum neeostratum 历经数百年至数千年缓慢形成的巨大钙质珊瑚礁，由于这两个过程之间出现的相互作用，现在正在减少。这些珊瑚礁是阿留申海带森林的结构基础，由于食草动物的过度放牧，正在迅速受到侵蚀。历史重建和实验表明，过度放牧是由海獭、EnHydra lutris（这导致了能够引起生物侵蚀的食草动物的产生）的消失引发的，然后随着海洋变暖和酸化而加速（导致人均致命放牧增加了 34% 至 60%）与工业化前时期相比）。因此，关键的捕食者可以调节气候影响在自然界中出现的方式以及它们改变生态系统的速度。