In fish, maximum O2 consumption rate (MO2max) and aerobic scope can be expanded following exhaustive exercise in hyperoxia; however, the mechanisms explaining this are yet to be identified. Here, in exhaustively exercised rainbow trout (Oncorhynchus mykiss), we assessed the influence of hyperoxia on MO2max, aerobic scope, cardiac function and blood parameters to address this knowledge gap. Relative to normoxia, MO2max was 33% higher under hyperoxia, and this drove a similar increase in aerobic scope. Cardiac output, due to increased stroke volume, was significantly elevated under hyperoxia at MO2max indicating hyperoxia released a constraint on cardiac contractility apparent with normoxia. Thus, hyperoxia improved maximal cardiac performance, thereby enhancing tissue O2 delivery and allowing a higher MO2max. Venous blood O2 partial pressure (PvO2) was elevated in hyperoxia at MO2max, suggesting a contribution of improved luminal O2 supply in enhanced cardiac contractility. Additionally, despite reduced haemoglobin and higher PvO2, hyperoxia treated fish retained a higher arterio-venous O2 content difference at MO2max. This may have been possible due to hyperoxia offsetting declines in arterial oxygenation known to occur following exhaustive exercise in normoxia. If this occurs, increased contractility at MO2max with hyperoxia may also relate to an improved O2 supply to the compact myocardium via the coronary artery. Our findings show MO2max and aerobic scope may be limited in normoxia following exhaustive exercise due to constrained maximal cardiac performance and highlight the need to further examine whether or not exhaustive exercise protocols are suitable for eliciting MO2max and estimating aerobic scope in rainbow trout.
2023 JEB Outstanding Paper Prize shortlist and winner
The JEB Editors are delighted to announce the shortlisted authors for the 2023 JEB Outstanding Paper Prize. Read the winning paper - Tiny spies: mosquito antennae are sensitive sensors for eavesdropping on frog calls - by Hoover Pantoja-Sanchez and Brian Leavell from Ximena Bernal's lab at Purdue University, USA.
JEB Science Communication Workshop for ECRs
If you’re an early-career researcher interested in science communication and are attending the SEB Annual Conference in Prague this summer, come a day early and join the JEB Editors at a sci comm workshop to learn the key writing skills needed to promote your research to a broad audience beyond your peers (1 July at 14.30-17.30). Places are limited to 24 attendees, and applicants should apply through the SEB registration page by 30 April 2024.
Bridging the gap between controlled conditions and natural habitats in understanding behaviour
Novel technologies enable behavioural experiments with non-model species, in naturalistic habitats and with underexplored behaviours. In their Commentary, Scholz and colleagues discuss how to obtain a deeper understanding of the natural ecology and lifestyle of study animals.
Beluga metabolic measures could help save species
To help save animals from extinction, it’s important to understand what each species needs to survive. This led Jason John et al. to measure the metabolic rates of captive belugas to develop a ‘fish calculator’ showing that the whales need to eat ~23 salmon per day.
ECR Workshop on Positive Peer Review
Are you an ECR looking for tips on how to write concise, astute and useful manuscript reviews? If so, join the JEB Editors at a 2-hour JEB-sponsored Workshop on Positive Peer Review at the Canadian Society of Zoologists annual meeting in Moncton on 9 May 2024 at 13.00-15.00. There are 25 spaces for ECRs and selection is first come, first serve. To sign up, check the ECR Workshop box when you register for the CSZ meeting.
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