Temperature effects on metabolic rate and cardiorespiratory physiology of the spiny rock lobster (Jasus edwardsii) during rest, emersion and recovery
AbstractAlthough spiny rock lobster (Jasus edwardsii) is a wholly sub-littoral species, they show a considerable ability to survive prolonged emersion, a fact exploited during the commercial export of this species. Yet, despite this remarkable hardiness, basic information on how this species responds physiologically to emersion is somewhat lacking. Using flow-through respirometry and electrophysiological techniques, we identified that J. edwardsii undergoes marked physiological changes during rest, emersion and recovery over a broad range of temperatures (3.7–17.8 °C). Under resting conditions, routine metabolic rates (RMR) were 22.57 ± 2.39, 9.69 ± 0.55 and 8.09 ± 0.27 mL O2 h−1, average heart rates (Hr) were 54.72 ± 4.46, 37.68 ± 2.86 and 29.67 ± 0.59 BPM, and ventilation frequencies were 83.71 ± 5.86, 45.34 ± 2.91 and 41.62 ± 0.65 BPM at 15.0, 7.5 and 3.7 °C, respectively. Notably, the surgical implantation of electrodes elevated RMR compared with non-surgical treatments. In surgery and non-surgery groups, Q10 was calculated to be ca. 3.0. Upon emersion, rate of oxygen consumption and Hr decreased below resting rates in a temperature-dependent manner, but, along with rate of CO2 production, increased steadily during 24-h emersion. Ventilation frequencies upon emersion showed a contrasting response and increased significantly above resting rates. When returned to flow-through sea water for recovery, elevated respiration rates provided clear evidence of an O2 debt, and near-complete recovery was observed after 17 h at both 15.0 and 7.5 °C, but close to no debt was recovered at 3.7 °C. In addition, J. edwardsii was observed to undergo marked diurnal and periodic ventilation cycles, characterised by synchronous changes in RMR, Hr and ventilation frequency.
