Natt Michael, Lönnstedt Oona M, McCormick Mark I
ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia.
Department of Marine Biology and Aquaculture, James Cook University, Townsville, Queensland, Australia.
PLoS One. 2017 Jun 28;12(6):e0179300. doi: 10.1371/journal.pone.0179300. eCollection 2017.
Coral reefs around the world are rapidly degrading due to a range of environmental stressors. Habitat degradation modifies the sensory landscape within which predator-prey interactions occur, with implications for olfactory-mediated behaviours. Predator naïve settlement-stage damselfish rely on conspecific damage-released odours (i.e., alarm odours) to inform risk assessments. Yet, species such as the Ambon damselfish, Pomacentrus amboinensis, become unable to respond appropriately to these cues when living in dead-degraded coral habitats, leading to increased mortality through loss of vigilance. Reef fish predators also rely on odours from damaged prey to locate, assess prey quality and engage in prey-stealing, but it is unknown whether their responses are also modified by the change to dead-degraded coral habitats. Implications for prey clearly depend on how their predatory counterparts are affected, therefore the present study tested whether olfactory-mediated foraging responses in the dusky dottyback, Pseudochromis fuscus, a common predator of P. amboinensis, were similarly affected by coral degradation. A y-maze was used to measure the ability of Ps. fuscus to detect and move towards odours, against different background water sources. Ps. fuscus were exposed to damage-released odours from juvenile P. amboinensis, or a control cue of seawater, against a background of seawater treated with either healthy or dead-degraded hard coral. Predators exhibited an increased time allocation to the chambers of y-mazes injected with damage-released odours, with comparable levels of response in both healthy and dead-degraded coral treated waters. In control treatments, where damage-released odours were replaced with a control seawater cue, fish showed no increased preference for either chamber of the y-maze. Our results suggest that olfactory-mediated foraging behaviours may persist in Ps. fuscus within dead-degraded coral habitats. Ps. fuscus may consequently gain a sensory advantage over P. amboinensis, potentially altering the outcome of predator-prey interactions.
由于一系列环境压力因素，世界各地的珊瑚礁正在迅速退化。栖息地退化改变了捕食者与猎物相互作用发生的感官环境，对嗅觉介导的行为产生影响。未接触过捕食者的定居阶段雀鲷依靠同种释放的损伤气味（即警报气味）来进行风险评估。然而，像安汶雀鲷（Pomacentrus amboinensis）这样的物种，当生活在死亡退化的珊瑚栖息地时，就无法对这些线索做出适当反应，从而因警惕性丧失而导致死亡率增加。珊瑚礁鱼类捕食者也依靠受损猎物的气味来定位、评估猎物质量并进行偷猎行为，但它们的反应是否也会因向死亡退化的珊瑚栖息地的转变而改变尚不清楚。对猎物的影响显然取决于它们相应的捕食者如何受到影响，因此本研究测试了暗体拟雀鲷（Pseudochromis fuscus）（安汶雀鲷的常见捕食者）的嗅觉介导的觅食反应是否同样受到珊瑚退化的影响。使用Y型迷宫来测量暗体拟雀鲷在不同背景水源下检测并朝着气味移动的能力。将暗体拟雀鲷暴露于来自幼年安汶雀鲷释放的损伤气味，或海水对照线索下，背景海水分别用健康或死亡退化的硬珊瑚处理。捕食者对注入损伤释放气味的Y型迷宫腔室的时间分配增加，在健康和死亡退化珊瑚处理的水中反应水平相当。在对照处理中，用对照海水线索代替损伤释放气味，鱼类对Y型迷宫的任一腔室均未表现出增加的偏好。我们的结果表明，嗅觉介导的觅食行为可能在死亡退化的珊瑚栖息地中的暗体拟雀鲷中持续存在。因此，暗体拟雀鲷可能比安汶雀鲷获得感官优势，潜在地改变捕食者与猎物相互作用的结果。
