# Does oxygen limitation set thermal limits in aquatic ectotherms?

## TL;DR

A new study questions the idea that oxygen shortage limits how well aquatic animals can handle heat, sparking new debate.

## Contribution

The study shows that oxygen supersaturation has little protective effect on aquatic ectotherms under heat stress.

## Key findings

- Oxygen limitation may not be the main factor in thermal tolerance of aquatic ectotherms.
- Supersaturated oxygen levels provided minimal protection during heat stress.
- The findings challenge the prevailing oxygen limitation hypothesis.

## Abstract

Thermal tolerance determines winners and losers in a warming world. Oxygen limitation has been the primary hypothesis for the mechanistic basis of thermal tolerance. A new study in PLOS Biology suggests otherwise, reigniting debate on what truly sets thermal limits.

Oxygen limitation is thought to represent a key mechanism underlying thermal tolerance. This primer discusses how a recent PLOS Biology article challenges this idea, by showing minimal protective effects of oxygen supersaturation in aquatic ectotherms exposed to heat stress.