The idea that the presence of sharks impacts the behavior of mesopredatory reef fishes is controversial and lacks clear evidence at reef‐wide scales. We compared the abundance and behavior of these reef fishes in response to the presence of reef sharks using Baited Remote Underwater Video System (BRUVS) deployments in two adjacent reef systems where sharks have either been exclusively targeted by fishing or protected by a no‐take marine reserve. For a subset of videos, we also compared the behavior of mesopredatory reef fishes immediately before and after the appearance of sharks in the video. On reefs where sharks were more abundant, mesopredatory fishes spent less time swimming in midwater (i.e., away from shelter) and guarding bait compared to reefs where sharks have been selectively removed. The same responses occurred after the appearance of sharks in the video. Reactions to sharks varied both in strength and type among species of mesopredator and were mediated by the availability of shelter on the reef and, for one species, by the levels of activity of the reef sharks. In contrast, we did not find that the presence of sharks influenced the abundance of mesopredators at either reef system across hour‐long videos or immediately before and after a shark appeared in the video. Collectively, our findings show that the presence of sharks reduces the propensity of mesopredatory fish to engage in potentially risk‐prone behaviors over large spatial scales and that these interactions are mediated by the behavioral characteristics of both predators and prey, and the environment in which they co‐occur. Our results are consistent with the idea that sharks as predators or larger competitors initiate changes in the behavior of mesopredatory reef fishes likely to affect trophic structuring within coral reef ecosystems.

中文翻译：

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礁石证据表明鲨鱼的存在改变了硬骨介壳虫的行为

鲨鱼的存在会影响中距离礁鱼的行为这一观点是有争议的，并且在整个礁石范围内都缺乏明确的证据。我们使用诱饵远程水下视频系统（BRUVS）部署在两个相邻的礁石系统中比较了这些礁石鱼的丰度和行为，以应对礁石鲨的存在，在两个相邻的礁石系统中，鲨鱼要么专门捕捞目标，要么受到不捕捞海洋生物的保护保留。对于视频的子集，我们还比较了视频中鲨鱼出现之前和之后的中捕礁鱼的行为。在鲨鱼较为丰富的珊瑚礁上，与选择性去除鲨鱼的珊瑚礁相比，中度捕捞鱼类在中水游泳（即远离庇护所）花费的时间更少。视频中出现鲨鱼后，出现了相同的响应。中鲨鱼对鲨鱼的反应在强度和类型上都不同，并且受礁石上庇护所的可用性和一种物种介导的礁石鲨鱼活动水平的介导。相比之下，我们没有发现鲨鱼的存在会影响整个小时视频中珊瑚礁系统中鲨鱼的数量，也不会影响鲨鱼出现在视频中的前后。总的来说，我们的研究结果表明，鲨鱼的存在降低了中捕性鱼类在大空间尺度上从事潜在易发风险行为的倾向，并且这些相互作用是由掠食者和猎物的行为特征以及它们所处的环境所介导的。同时发生。