Trujillo José E, Bouyoucos Ian A, Weideli Ornella C, Milanesi Elena M C, Debaere Shamil F, Rayment William J, Planes Serge, Domenici Paolo, Rummer Jodie L, Allan Bridie J M
Department of Marine Science, University of Otago, 362 Leith Street North, Dunedin 9016, New Zealand.
Australian Research Council Centre of Excellence for Coral Reef Studies, College of Science and Engineering, James Cook University, 1 James Cook Dr, Townsville, QLD 4811, Australia.
Conserv Physiol. 2025 Aug 4;13(1):coaf045. doi: 10.1093/conphys/coaf045. eCollection 2025.
The prevailing shark nursery paradigm suggests that high survival in these habitats is primarily driven by reduced predator encounters: so-called pre-encounter risk. In this study, we propose an alternative or complementary mechanism: that some nurseries may lower post-encounter risk by providing environmental conditions that maximize escape performance. To test this hypothesis, we examined how temperature, depth and habitat complexity influence the escape performance of newborn blacktip reef sharks () in Mo'orea, French Polynesia. In a controlled setting, we exposed 48 newborn sharks to four temperature treatments (25, 27, 29 and 31°C) and measured fast-start acceleration, turning rate and latency to respond to a stimulus. We also calculated aerobic scope at 27, 29 and 31°C, as greater aerobic scope is associated with faster recovery from burst swimming. Our results show that warmer temperatures improve escape performance, with 29% higher acceleration, 9% faster turning rates and 48% shorter reaction times at elevated temperatures. Furthermore, aerobic scope remained ≥80% of its maximum capacity between 27.5 and 30.8°C, suggesting that newborn sharks can sustain high metabolic performance within this thermal window. Field measurements at nursery habitats revealed that daily thermal fluctuations generally remained within this optimal aerobic scope range, meaning that newborns can maintain high escape performance for most of the day. Additionally, high-resolution mapping confirmed that previously reported home ranges were associated with shallow (median depth = 0.74 m), structurally complex reef flats dominated by coral substrate. The combination of reduced hydrodynamic drag in shallow water and increased manoeuvrability in complex habitats likely enhances predator evasion. However, extreme warming events that exceed critical thermal limits may trigger behavioural trade-offs that compromise escape performance and elevate predation risk. Our findings suggest that these nurseries provide habitat-specific advantages for predator evasion, reinforcing their critical role in the survival of newborn sharks.
普遍的鲨鱼育幼模式表明，这些栖息地中高存活率主要是由减少与捕食者的相遇所驱动的：即所谓的相遇前风险。在本研究中，我们提出了一种替代或补充机制：一些育幼场可能通过提供能使逃逸能力最大化的环境条件来降低相遇后风险。为了验证这一假设，我们研究了温度、深度和栖息地复杂性如何影响法属波利尼西亚莫雷阿岛新生黑鳍礁鲨（）的逃逸能力。在一个可控环境中，我们将48条新生鲨鱼置于四种温度处理条件下（25、27、29和31°C），并测量快速启动加速度、转弯速率以及对刺激做出反应的潜伏期。我们还计算了27、29和31°C时的有氧代谢范围，因为更大的有氧代谢范围与爆发式游泳后更快的恢复相关。我们的结果表明，温度升高能改善逃逸能力，在高温下加速度提高29%，转弯速率加快9%，反应时间缩短48%。此外，在27.5至30.8°C之间，有氧代谢范围保持在其最大容量的≥80%，这表明新生鲨鱼能在这个温度窗口内维持较高的代谢表现。在育幼栖息地的实地测量显示，每日温度波动通常保持在这个最佳有氧代谢范围之内，这意味着新生鲨鱼在一天中的大部分时间都能保持较高的逃逸能力。此外，高分辨率绘图证实，先前报道的活动范围与浅水区（中位深度 = 0.74米）、以珊瑚基质为主的结构复杂的礁坪有关。浅水区水动力阻力降低以及复杂栖息地中机动性增加的综合作用可能增强了对捕食者的躲避能力。然而，超过临界温度极限的极端变暖事件可能引发行为权衡，从而损害逃逸能力并提高被捕食风险。我们的研究结果表明，这些育幼场为躲避捕食者提供了特定于栖息地的优势，强化了它们在新生鲨鱼生存中的关键作用。
