Open-top static respirometry is a reliable method to determine the routine metabolic rate of barramundi, Lates calcarifer

Closed-system respirometry is a standard technique used to determine aerobic metabolism of aquatic organisms. Open-top systems are rarely used due to concerns of gas exchange across the air-water interface. Here, we evaluated an open-top respirometry system by comparing the mass-specific routine metabolic rate (RMR) of the tropical diadromous finfish barramundi, Lates calcarifer, in both closed-top and open-top respirometers. The RMR of 190 g barramundi was determined across broad temperatures ranging from 18 to 38 °C. There was no significant difference in RMR between barramundi in either closed- or open-top respirometers at any temperature (p > 0.05). To ensure RMR measurements were not an artifact of the respirometry system, barramundi were reciprocally transplanted into either respective closed-top or open-top respirometer and oxygen consumption re-measured at each temperature treatment. The RMR of transplanted barramundi was found to be virtually identical in either respirometer. RMR increased linearly with increasing temperature; the relationship between RMR and temperature (T; 18-38 °C) can be described as 3.658T-36.294 mg O2 kg-0.8 h-1. The daily energetic cost of RMR was 1.193T-11.838 kJ kg-0.8 day-1. Q10 for barramundi increased significantly with increasing temperature (p < 0.0001). Q10(18-28) was the lowest at 1.7 and Q10(28-38) the highest at 1.9, over the whole experiment temp range Q10(18-28) was 1.8. The current study demonstrates that open-top respirometry is a reliable and practical alternative to closed-top respirometry for accurate determination of the aerobic metabolism of barramundi and has potential application for a number of different aquatic organisms. © 2014 © 2014 Taylor & Francis.