Direct exploitation through fishing is driving dramatic declines of wildlife populations in ocean environments, particularly for predatory and large-bodied taxa. Despite wide recognition of this pattern and well-established consequences of such trophic downgrading on ecosystem function, there have been few empirical studies examining the effects of fishing on whole system trophic architecture. Understanding these kinds of structural impacts is especially important in coral reef ecosystems-often heavily fished and facing multiple stressors. Given the often high dietary flexibility and numerous functional redundancies in diverse ecosystems such as coral reefs, it is important to establish whether web architecture is strongly impacted by fishing pressure or whether it might be resilient, at least to moderate-intensity pressure. To examine this question, we used a combination of bulk and compound-specific stable isotope analyses measured across a range of predatory and low-trophic-level consumers between two coral reef ecosystems that differed with respect to fishing pressure but otherwise remained largely similar. We found that even in a high-diversity system with relatively modest fishing pressure, there were strong reductions in the trophic position (TP) of the three highest TP consumers examined in the fished system but no effects on the TP of lower-level consumers. We saw no evidence that this shortening of the affected food webs was being driven by changes in basal resource consumption, for example, through changes in the spatial location of foraging by consumers. Instead, this likely reflected internal changes in food web architecture, suggesting that even in diverse systems and with relatively modest pressure, human harvest causes significant compressions in food chain length. This observed shortening of these food webs may have many important emergent ecological consequences for the functioning of ecosystems impacted by fishing or hunting. Such important structural shifts may be widespread but unnoticed by traditional surveys. This insight may also be useful for applied ecosystem managers grappling with choices about the relative importance of protection for remote and pristine areas and the value of strict no-take areas to protect not just the raw constituents of systems affected by fishing and hunting but also the health and functionality of whole systems.

中文翻译：

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与未捕捞的珊瑚礁相比，捕捞的珊瑚礁食物链长度缩短。


通过捕捞进行的直接开发正在导致海洋环境中野生动物数量的急剧下降，特别是掠食性和大型类群。尽管人们广泛认识到这种模式以及这种营养降级对生态系统功能的影响，但很少有实证研究考察捕捞对整个系统营养结构的影响。了解这些类型的结构性影响对于珊瑚礁生态系统尤其重要，因为珊瑚礁生态系统通常遭到大量捕捞并面临多种压力。鉴于珊瑚礁等不同生态系统通常具有较高的饮食灵活性和大量的功能冗余，因此确定网结构是否受到捕捞压力的强烈影响或者是否具有弹性（至少能够承受中等强度的压力）非常重要。为了研究这个问题，我们结合了大量和特定化合物的稳定同位素分析，对两个珊瑚礁生态系统之间的一系列掠夺性和低营养级消费者进行了测量，这两个珊瑚礁生态系统在捕捞压力方面有所不同，但在其他方面仍然基本相似。我们发现，即使在捕捞压力相对较小的高多样性系统中，在捕捞系统中检查的三个最高 TP 消费者的营养位置 (TP) 也大幅下降，但对较低级别消费者的 TP 没有影响。我们没有看到任何证据表明受影响食物网的缩短是由基础资源消耗的变化驱动的，例如，通过消费者觅食的空间位置的变化。 相反，这可能反映了食物网结构的内部变化，表明即使在不同的系统中并且压力相对较小，人类的收获也会导致食物链长度的显着压缩。观察到的这些食物网的缩短可能会对受捕鱼或狩猎影响的生态系统的功能产生许多重要的紧急生态后果。这种重要的结构性转变可能很普遍，但传统调查却没有注意到。这种见解对于应用生态系统管理者来说也可能有用，他们需要选择保护偏远和原始地区的相对重要性，以及严格禁渔区的价值，不仅保护受捕鱼和狩猎影响的系统的原始组成部分，而且还保护受捕捞和狩猎影响的系统的原始成分。整个系统的健康和功能。