Predicting the effects of predator diversity loss on food webs is challenging, because predators can both consume and induce behavioral responses in their prey (i.e., non-consumptive effects or NCEs). Studies manipulating predator diversity and investigating NCEs are rare, especially in marine systems. Recently, a severe outbreak of sea star wasting syndrome (SSWS) on the west coast of North America resulted in unprecedented declines of the sea star Pisaster ochraceus. We investigated the consequences of Pisaster loss on an abundant grazer, the black turban snail Tegula funebralis, through NCEs. We combined a laboratory experiment and field surveys to examine the importance of identity vs. diversity in a predator assemblage (Pisaster, crabs, and octopuses) on Tegula behavior, feeding, and growth. Laboratory and field results indicated that predator identity, not diversity, drives Tegula behavior and causes NCEs. Mesocosm treatments with Pisaster caused greater NCEs on Tegula than assemblages without Pisaster. Tegula's distribution in the field, which is driven primarily by anti-predator behavior, was strongly associated only with Pisaster abundance, and not with the abundance of crabs, octopuses, and other predatory sea stars (Leptasterias spp.). We conclude that Pisaster primarily drives Tegula vertical distribution and may be having strong NCEs on Tegula on northern California rocky shores. Furthermore, predator diversity in northern California does not provide functional redundancy, in terms of NCEs on Tegula, to buffer the system from Pisaster loss. Thus, predator-induced vertical distributions and grazing suppression may not be maintained in areas where Pisaster populations are reduced or slow to recover from SSWS.

中文翻译：

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食肉动物的身份在受疾病影响的多岩石的海岸食物网中占据着非食用性的主导地位。

预测捕食者多样性丧失对食物网的影响具有挑战性，因为捕食者既可以消耗食物，又可以在其食物中引起行为反应（即非消耗性影响或NCE）。操纵捕食者多样性和调查NCE的研究很少，尤其是在海洋系统中。最近，在北美西海岸爆发了严重的海星浪费综合症（SSWS），导致海星Pisaster ochraceus的空前下降。我们通过NCE调查了Pisaster损失对大量放牧者，黑色头巾蜗牛Tegula funebralis造成的后果。我们结合了实验室实验和田野调查，以研究在天敌行为，摄食和生长方面，捕食者组合（Pisaster，螃蟹和章鱼）中身份与多样性的重要性。实验室和野外调查结果表明，捕食者的身份而非多样性会驱动特古拉的行为并引起NCE。用Pisaster进行介观治疗比不使用Pisaster的组合在Tegula上引起更大的NCE。Tegula在野外的分布主要由反掠食者的行为决定，仅与Pisaster的丰富度密切相关，与螃蟹，章鱼和其他掠食性海星的丰富度没有明显关系（Leptasterias spp。）。我们得出的结论是，Pisaster主要推动了Tegula的垂直分布，并且在加利福尼亚北部多岩石海岸的Tegula上可能具有较强的NCE。此外，就特古拉（Tegula）上的NCE而言，北加州的捕食者多样性不能提供功能上的冗余，以防止Pisaster损失。从而，