DOI: 10.5061/dryad.3n5tb2rvm
title: Decoding thermal resilience in fish: Acute warming tolerance is associated with neural failure in rainbow trout

description: As an effect of climate change, heat waves pose an increasingly more
 frequent and severe threat to fish populations. Yet, the physiological
 mechanisms underlying thermal tolerance in fish remain unclear. One
 hypothesis is that thermal tolerance may be limited by neural failure at
 high temperatures. Here, we used an electrophysiological approach to test
 this by assessing the relationship between brain function, determined via
 recordings of visually evoked responses (VERs) on the electroencephalogram
 (EEG), and cardioventilatory performance, determined via recordings of
 ventilatory electromyography (EMG) and electrocardiogram (ECG), in adult
 rainbow trout (Oncorhynchus mykiss) exposed to a critical thermal maximum
 (CTmax) protocol. Our results show that normal brain function is preserved
 at moderate to high temperatures, however, at CTmax, the fish exhibited
 loss of VERs indicating brain dysfunction associated with insensibility.
 This suggests a strong link between neural failure and upper thermal
 tolerance in fish. Although heart and ventilatory rates increased with
 warming, heart rate significantly declined at CTmax. Interestingly,
 ventilation rate remained high even at extreme temperatures and at CTmax,
 indicating that neural ventilatory drive was maintained across thermal
 extremes. The factors underlying thermally induced neural failure and its
 implications for fish in a warming world require further investigations.
description: # Decoding thermal resilience in fish: Acute warming tolerance is
 associated with neural failure in rainbow trout Dataset DOI:
 [10.5061/dryad.3n5tb2rvm](10.5061/dryad.3n5tb2rvm) ## Description of the
 data and file structure The current dataset
 (`Dataset_-_Ekström_et_al.__-_Decoding_thermal_resilience_in_fish_-_Acute_warming_tolerance_is_associated_with_neural_failure_in_rainbow_trout.xlsx `) contains the supporting data for the findings published in our paper entitled "Decoding thermal resilience in fish - Acute warming tolerance is associated with neural failure in rainbow trout", published in Biology Letters ([https://doi.org/10.1098/rsbl.2025.0132](https://doi.org/10.1098/rsbl.2025.0132)). In this study, we applied an electrophysiological method to investigate the link between brain activity and cardioventilatory function in adult rainbow trout (*Oncorhynchus mykiss*) subjected to a critical thermal maximum (CTmax) protocol. Fish were exposed to 10, 15, 20 and 25 degrees, until they reached the temperature at which they reached CTmax. Brain function was evaluated using electroencephalogram (EEG) recordings of visually evoked responses (VERs), while cardioventilatory performance was assessed through simultaneous recordings of ventilatory electromyography (EMG) to determine ventilation rate (breaths min-1) and electrocardiogram (ECG) to determine heart rate (beats min-1). See the published paper for more information) The Excel file is divided into three datasheets, labelled according to the name of each figure in the paper that illustrates the data. **Figure 2A:** This data illustrates whether VERs were present or not present at each temperature exposure level (Column B) and at CTmax (Column C) in each individual fish (column A). The presence (yes/no) of VERs was assessed by a Cochran´s Q test. Significant main effects were further evaluated with pairwise comparisons across temperatures with multiple McNemar tests with Bonferroni corrections. **Figure 2B:** This data reflects the effect of temperature (Column B) on VERs amplitude (Column C, in uV) and % change from baseline (Column D) in each individual fish (Column A). **Figure 2C,D:** This data reflects the effect of temperature (Column B) on Heart rate (Column C) and ventilation rate (Column D) in each individual fish (Column A). The impacts of temperature on these variables were assessed by a Linear mixed model. Linear mixed models were performed with individual values for heart rate and ventilation rate as the dependent variables, and temperature levels (10°C, 15°C, 20°C, 25°C, and CTmax) as the independent repeated measures variable. Significant main effects were further evaluated with Bonferroni-corrected pairwise comparisons across temperatures. Cells with n/a (=not applicable) indicate that no data was attainable for that individual fish.