Graham D. Raby | Lightnews

Graham Raby @graham-raby.bsky.social · 7d

In this new study, we provide new data relevant to the debate about whether oxygen limitation is a universal driver of thermal tolerance in water breathing animals.

News story: www.trentu.ca/news/story/2...

Paper: journals.plos.org/plosbiology/...

Primer: journals.plos.org/plosbiology/...

More Oxygen Won’t Save Fish from Warming Waters

Trent study helps inform long-standing theory about increasing oxygen levels in higher water temperatures to support heat tolerance in aquatic species

www.trentu.ca

PLOS Biology @plosbiology.org · 19d

Oxygen limitation is considered a key mechanism of #ThermalTolerance. @dianasmadeira.bsky.social explores how a @plosbiology.org study challenges this idea, showing minimal protective effects of O2 supersaturation in heat-stressed #aquatic #ectotherms 🧪 Paper: plos.io/43hzMQa Primer: plos.io/3XeUtbS

The effects of temperature on organismal performance are depicted using thermal performance curves, where performance is greatest at the optimal temperature and starts to decrease toward cooler or warmer temperatures, reflecting the thermal window (tolerable range of temperatures) of the species. Briefly, the Oxygen and Capacity Limited Thermal Tolerance hypothesis proposes that oxygen limitation explains the performance decline at high temperatures and sets the first boundary for thermal limits across ectotherms. This is due to a mismatch between the oxygen demand of the organism and the capacity of the cardiorespiratory system to supply oxygen to tissues when the organism is under warming. This concept is central to predict species responses to warming. As oxygen supersaturation in water has been shown to alleviate oxygen supply limitations by increasing maximum rates of oxygen transport in blood, Raby and colleagues (2025) tested the effects of oxygen supersaturation on thermal tolerance across 14 aquatic species. The authors found that it had negligible effects on upper thermal limits, challenging the oxygen limitation hypothesis as a universal mechanism underpinning thermal tolerance of aquatic ectotherms. The authors highlight that oxygen supersaturation in water, a naturally occurring phenomenon in shallow waters, may not protect aquatic species from the effects of extreme heat.

Graham Raby @graham-raby.bsky.social · 19d

Very exciting to finally have this work out there. Thanks to the team at @plosbiology.org for being willing to publish null results!

PLOS Biology @plosbiology.org · 19d

Oxygen supersaturation is proposed to buffer against #HeatStress in water-breathing animals. @graham-raby.bsky.social @jutfelt.bsky.social &co re-examine this question in diverse #aquatic #ectotherms, showing that #hyperoxia has minimal impact on thermal tolerance @plosbiology.org 🧪 plos.io/43hzMQa

Effect of hyperoxia (150% air saturation) on warming tolerance in 14 aquatic ectotherms from across the globe. Left: Forest plot showing effect sizes (model estimates ± 95% confidence intervals) for the effect of hyperoxia on warming tolerance. Black symbols are the fast warming (0.3°C min−1) trials, blue symbols are the slow warming (1°C h−1) trials, and yellow symbols are for a net combined effect with random effects for subgroups of the 24 experiments. The effects were considered statistically significant where the 95% confidence interval does not cross the red vertical line. Right: Approximate geographical distributions for the 10 species of fish (top) and four species of decapod crustaceans (bottom) used in the laboratory experiments to assess the effects of hyperoxia on upper thermal tolerance.

PLOS Biology @plosbiology.org · 19d

Oxygen limitation is considered a key mechanism of #ThermalTolerance. @dianasmadeira.bsky.social explores how a @plosbiology.org study challenges this idea, showing minimal protective effects of O2 supersaturation in heat-stressed #aquatic #ectotherms 🧪 Paper: plos.io/43hzMQa Primer: plos.io/3XeUtbS

PLOS Biology @plosbiology.org · 19d

Oxygen supersaturation is proposed to buffer against #HeatStress in water-breathing animals. @graham-raby.bsky.social @jutfelt.bsky.social &co re-examine this question in diverse #aquatic #ectotherms, showing that #hyperoxia has minimal impact on thermal tolerance @plosbiology.org 🧪 plos.io/43hzMQa

Graham Raby @graham-raby.bsky.social · 19d

Special thanks to @dianasmadeira.bsky.social for authoring this thoughtful primer about the study we published this week in @plosbiology.org Good suggestions about all the work we still need to do to unveil the mechanisms underlying variation in thermal tolerance.

journals.plos.org/plosbiology/...

PLOS Biology @plosbiology.org · 20d

Oxygen supersaturation is proposed to buffer against #HeatStress in water-breathing animals. @graham-raby.bsky.social @jutfelt.bsky.social &co re-examine this question in diverse #aquatic #ectotherms, showing that #hyperoxia has minimal impact on thermal tolerance @plosbiology.org 🧪 plos.io/43hzMQa

PLOS Biology @plosbiology.org · 20d

Oxygen supersaturation is proposed to buffer against #HeatStress in water-breathing animals. @graham-raby.bsky.social @jutfelt.bsky.social &co re-examine this question in diverse #aquatic #ectotherms, showing that #hyperoxia has minimal impact on thermal tolerance @plosbiology.org 🧪 plos.io/43hzMQa

Fredrik Jutfelt 🐠 @jutfelt.bsky.social · 20d

Oxygen supersaturation has been reported to protect aquatic animals from heat waves. We tested this in a large collaborative experiment on many species of fish and crustaceans. Our new paper in @plosbiology.org shows that the effect of hyperoxia on thermal tolerance is negligible. Unfortunately.

cars-afs.bsky.social @cars-afs.bsky.social · 23d

CONGRATULATIONS!
Larkin Award, PhD Winner
#BradleyHowell
🪼
[Graham Raby, #TrentUniversity & Steven Cooke, #CarletonUniversity]
🪼
Bradley’s research focuses on using telemetry and respirometry data to assess #predatorprey interactions and movement patterns that raise predation risk.

Graham Raby @graham-raby.bsky.social · Oct 23

Boat salad

Graham Raby @graham-raby.bsky.social · Oct 16

We have the most photogenic campus

Gary Burness @garyburness.bsky.social · Oct 1

Excited about a new preprint from PhD candidate Megan Heft, showing that nestling provisioning rates in male tree swallows are not limited by the male's risk of overheating (in contrast with previous studies of females) 🧪 #ornithology #science
www.biorxiv.org/content/bior...

www.biorxiv.org