Data from: Paradoxical escape responses by narwhals (Monodon monoceros)

Until recent declines in Arctic sea ice levels, narwhals (Monodon monoceros) have lived in relative isolation from human perturbation and sustained predation pressures. The resulting naïvety has made this cryptic, deep-diving cetacean highly susceptible to disturbance, although quantifiable effects have been lacking. We deployed a submersible, animal-borne electrocardiograph-accelerometer-depth recorder to monitor physiological and behavioral responses of East Greenland narwhals after release from net entanglement and stranding. Escaping narwhals displayed a paradoxical cardiovascular down-regulation (extreme bradycardia with heart rate ≤4 beats per minute) superimposed on exercise up-regulation (stroke frequency >25 strokes per minute and energetic costs three to six times the resting rate of energy expenditure) that rapidly depleted onboard oxygen stores. We attribute this unusual reaction to opposing cardiovascular signals—from diving, exercise, and neurocognitive fear responses—that challenge physiological homeostasis.

在北极海冰面积近期出现下降之前，一角鲸（Monodon monoceros）始终生活在几乎不受人类活动扰动、未承受持续性捕食压力的相对隔绝环境中。由此产生的生存无知性，使得这种隐秘的深潜鲸类极易受到外界干扰，尽管此前一直缺乏相关可量化影响研究。我们部署了一款可潜水的动物搭载式心电图（electrocardiograph）-加速度计（accelerometer）-深度记录仪，以监测东格陵兰海域一角鲸在摆脱渔网缠绕与搁浅后的生理与行为响应。正在逃生的一角鲸展现出一种矛盾的心血管调节下调现象：心率低至每分钟≤4次的极端心动过缓（bradycardia），同时伴随运动上调——游泳划动频率超过每分钟25次，能量消耗达到静息代谢率的3至6倍——这一状况会快速耗尽其体内储氧量。我们将这一异常反应归因于来自潜水、运动以及神经认知层面恐惧反应的相悖心血管信号，这些信号共同挑战了生理内稳态（homeostasis）的平衡。