Air breathing in the Arctic: influence of temperature, hypoxia, activity and restricted air access on respiratory physiology of the Alaska blackfish Dallia pectoralis

作者：Lefevre Sjannie^*; Damsgaard Christian; Pascale Desirae R; Nilsson Goran E; Stecyk Jonathan A W

来源：Journal of Experimental Biology, 2014, 217(24): 4387-4398.

DOI：10.1242/jeb.105023

• respiratory partitioning
• bimodal respirometry
• temperature acclimation
• critical oxygen tension
• haemoglobin oxygen affinity
• gill remodelling

The Alaska blackfish (Dallia pectoralis) is an air-breathing fish native to Alaska and the Bering Sea islands, where it inhabits lakes that are ice-covered in the winter, but enters warm and hypoxic waters in the summer to forage and reproduce. To understand the respiratory physiology of this species under these conditions and the selective pressures that maintain the ability to breathe air, we acclimated fish to 5 degrees C and 15 degrees C and used respirometry to measure: standard oxygen uptake ((M) over dot(O2)) in normoxia (19.8 kPa P-O2) and hypoxia (2.5 kPa), with and without access to air; partitioning of standard (M) over dot(O2) in normoxia and hypoxia; maximum (M) over dot(O2) and partitioning after exercise; and critical oxygen tension (P-crit). Additionally, the effects of temperature acclimation on haematocrit, haemoglobin oxygen affinity and gill morphology were assessed. Standard (M) over dot(O2) was higher, but air breathing was not increased, at 15 degrees C or after exercise at both temperatures. Fish acclimated to 5 degrees C or 1 degrees C increased air breathing to compensate and fully maintain standard (M) over dot(O2) in hypoxia. Fish were able to maintain (M) over dot(O2) through aquatic respiration when air was denied in normoxia, but when air was denied in hypoxia, standard (M) over dot(O2) was reduced by similar to 30-50%. P-crit was relatively high (5 kPa) and there were no differences in P-crit, gill morphology, haematocrit or haemoglobin oxygen affinity at the two temperatures. Therefore, Alaska blackfish depends on air breathing in hypoxia and additional mechanisms must thus be utilised to survive hypoxic submergence during the winter, such as hypoxia-induced enhancement in the capacities for carrying and binding blood oxygen, behavioural avoidance of hypoxia and suppression of metabolic rate.

• 出版日期2014-12