Does hydrostatic pressure influence lumpfish (<i>Cyclopterus lumpus</i>) heart rate and its response to environmental challenges?

Abstract Studies on the effects of environmental changes with increasing depth (e.g. temperature and oxygen level) fish physiology rarely consider how hydrostatic pressure might influence observed responses. In this study, lumpfish (Cyclopterus lumpus, 200–400 g), which can exhibit vertical migrations over 100 m daily be found at depths 500 or more, were implanted Star-Oddi micro-HRT loggers. Then, their heart rate (fH) was measured in a chamber when exposed to following: (i) (up 80 bar; 800 depth) 10°C (ii) (12–20°C), decreasing (12 4°C) levels (101–55% air saturation 12°C) absence presence bar pressure. Additionally, we determined fH response chasing (to 22°C) atmospheric Pressure-induced increases from 48 61 bpm associated hyperactivity. The magnitude rise greater pressure-exposed vs. control (i.e. by ~30 45 between 5°C 20°C). However, relative increase slope relationship) not different groups. contrast, eliminated small (5 bpm) hypoxia. Exhaustive exercise 22°C resulted maximum 77 81 bpm, respectively. Our research shows that influences challenges provides first evidence have limited capacity fH.