A reduced susceptibility for local and global impacts has been assigned for deeper reefs compared to historically degraded shallow reefs. Yet, few studies have attempted to analyze the influence of depth on reef fish escape behavior across distinct size classes. By using behavioral response as a measure for prey wariness, the present study analyzed flight initiation distance (FID) for three fishery target and one non-target reef fish species on shallow and deeper reefs in South Atlantic Ocean (Multiple use MPA Costa dos Corais, Pernambuco State). We hypothesized that fish on shallow reefs would have higher FID and detect the human approach sooner and flee at a large distance than individuals in deeper reefs, which would have a late detection, allowing a closer approach. During our field experiment, flight initiation distances average was higher at shallow reefs for three analyzed species, yet each species had specific responses according to individual size classes. For two fishery target species E. adscensionis and C. fulva, two intermediate size classes presented higher flight distances at shallow than deeper reefs. However, S. axillare a target parrotfish, demonstrated an unexpected trend with higher FID on deeper reefs for smaller size classes. Interestingly, the non-target species, have also shown differences on wariness across the two analyzed size classes, with higher FID on shallow than deeper reefs. Our results suggest that fish on shallow reefs would detect the human approach sooner and flee at a large distance than individuals in deeper reefs; however, fish response to human presence according to depth is size classes and species dependent. We emphasis the important of no-take zones and the establishment of new marine protected areas on both shallow and deeper reefs in Brazilian waters and elsewhere in order to maintain the integrity of reef fish behavior and consequently ecosystems functioning.

中文翻译：

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深度对珊瑚鱼飞行起始距离的影响：深部珊瑚礁保护的影响

与历史上退化的浅礁相比，较深的珊瑚礁对局部和全球影响的敏感性降低。然而，很少有研究试图分析深度对不同大小级别的珊瑚鱼逃逸行为的影响。通过使用行为反应作为衡量猎物警惕性的衡量标准，本研究分析了南大西洋浅层和深层珊瑚礁上三种渔业目标和一种非目标珊瑚礁鱼类的飞行起始距离 (FID)（多次使用 MPA Costa dos Corais，伯南布哥州）。我们假设浅礁上的鱼会比深礁中的鱼有更高的 FID 并且更快地检测到人类的接近并逃离很远的距离，而深礁中的鱼会发现较晚，从而可以更近地接近。在我们的田间试验中，三个被分析物种在浅礁的平均飞行起始距离较高，但每个物种根据个体大小等级都有特定的反应。对于两个渔业目标物种 E. adscensionis 和 C. fulva，两个中等大小级别在浅水区的飞行距离比在更深的珊瑚礁上的飞行距离要长。然而，S. axillare 是一种目标鹦嘴鱼，表现出意想不到的趋势，在更深的珊瑚礁上，对于较小的尺寸等级，具有更高的 FID。有趣的是，非目标物种在两个分析的大小等级之间也表现出不同的警惕性，浅部珊瑚礁的 FID 高于深部珊瑚礁。我们的结果表明，浅礁上的鱼会比深礁中的鱼更早地发现人类的接近并逃跑更远的距离；然而，根据深度，鱼类对人类存在的反应取决于大小等级和物种。我们强调禁止捕捞区和在巴西水域和其他地方的浅水和深水珊瑚礁上建立新的海洋保护区的重要性，以保持珊瑚鱼行为的完整性，从而维持生态系统的功能。