Physiological responses of narwhals to anthropogenic noise: A case study with seismic airguns and vessel traffic in the Arctic

Abstract Limited polar geographical range, narrowly defined migratory routes, and deep‐diving behaviours make narwhals exceptionally vulnerable to anthropogenic disturbances including oceanic noise. Although behavioural studies indicate marked responses of cetaceans disturbance, the link between fear reactions possible injury from noise exposure is limited for most species. To address this, we deployed custom‐made heart rate‐accelerometer‐depth recorders on 13 adult in Scoresby Sound, East Greenland across a five‐year period (2014–2018). Physiological were monitored absence ( n = animals) or presence 2 animals 3 acoustic events) experimentally directed, seismic airgun pulses associated vessels (full volume source level 241 dB re 1 μPa‐m). We found that resulted cardiovascular, respiratory locomotor by two exposed three events. The general response vessel included an 80% reduction duration gliding during dive descents seismic‐exposed compared controls, prolongation high intensity activity (ODBA > 0.20 g ) with elevated stroke frequencies exceeding 40 strokes per minute. Noise also intense (<10 bpm) bradycardia was decoupled stroking frequency. This decoupling instigated increased variability rate, switching rapidly exercise tachycardia exposure. maximum frequency following exposure, 12 breaths/min, 1.5 times control levels. Overall, effect seismic/ship Arctic 2.0–2.2‐fold increase energetic cost diving, which paradoxically occurred suppression cardiac response. unusual relationship diving rate represents new metric characterizing wild marine mammals different environmental stressors. Together, multi‐level this cetacean demonstrated how cascade effects along entire oxygen pathway could challenge physiological homeostasis especially if disturbance prolonged. Read free Plain Language Summary article Journal blog.