Increasing evidence shows that larger fish are more vulnerable to acute warming than smaller individuals of the same species. This size-dependency of thermal tolerance has been ascribed to differences in aerobic performance, largely due to a decline in oxygen supply relative to demand. To shed light on these ideas, we examined metabolic allometry in 130 rainbow trout ranging from 12 to 358 g under control conditions (17°C) and in response to acute heating (to 25°C), with and without supplemental oxygen (100% versus 150% air saturation). Under normoxia, high temperature caused an average 17% reduction in aerobic scope compared with 17°C. Aerobic performance disproportionally deteriorated in bigger fish as the scaling exponent (b) for aerobic scope declined from b=0.87 at 17°C to b=0.74 at 25°C. Hyperoxia increased maximum metabolic rate and aerobic scope at both temperatures and disproportionally benefited larger fish at 25°C as the scaling exponent for aerobic scope was reestablished to the same level as at 17°C (b=0.86). This suggests that hyperoxia may provide metabolic refuge for larger individuals, allowing them to sustain aerobic activities when facing acute warming. Notably, the elevated aerobic capacity afforded by hyperoxia did not appear to improve thermal resilience, as mortality in 25°C hyperoxia (13.8%, n=4) was similar to that in normoxia (12.1%, n=4), although we caution that this topic warrants more targeted research. We highlight the need for mechanistic investigations of the oxygen transport system to determine the consequences of differential metabolic scaling across temperature in a climate warming context.
Hyperoxia disproportionally benefits the aerobic performance of large fish at elevated temperature
Call for Papers: The Integrative Biology of the Gut. Guest Editors Carol Bucking, Matt Regan and John Terblanche
We are pleased to welcome submissions for our upcoming Special Issue: The Integrative Biology of the Gut . We are calling for forward-looking papers that address the functional roles of the gut. We will consider papers that address gut function from the cellular level to its interactions with other organs and tissues, including its role in diverse ecophysiological processes, spanning both vertebrate and invertebrate species. The deadline for submission to this issue is 1 October 2024.
Extraordinary creatures: notothenioids and icefish
In our new Conversation focusing on extraordinary creatures, Christina Cheng and Kristin O'Brien tell us about the remarkable freeze tolerant nototheniods that live in the waters around Antarctica and how icefish are the only adult vertebrates that survive without haemoglobin.
Why are microclimates essential for predicting climate change responses and how to measure them?
In their Commentary, Duncan Mitchell and colleagues discuss problems with predicting terrestrial animals’ responses to a warming world based on air temperature, rather than the microclimate of their thermal environment. They provide a simple, low-cost approach to microclimate measurements to provide a more realistic assessment of terrestrial animal performance and predicted population responses in hot regions under warming conditions. This approach requires measuring the variables involved in the exchange of heat and water vapour between animals and their environment.
Turkey vultures defy thin air by flying faster
Turkey vultures successfully fly at high altitude despite the challenge of generating lift in thin air, but how? Jonathan Rader & Ty Hedrick discovered that the birds fly 1m/s faster at 2200m than at sea level to generate sufficient lift to remain aloft.
Biologists @ 100 - join us in Liverpool in March 2025
We are excited to invite you to a unique scientific conference, celebrating the 100-year anniversary of The Company of Biologists, and bringing together our different communities. The conference will incorporate the Spring Meetings of the BSCB and the BSDB, the JEB Symposium Sensory Perception in a Changing World and a DMM programme on antimicrobial resistance. Find out more and register your interest to join us in March 2025 in Liverpool, UK.
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