DOI: 10.5061/dryad.vdncjsz5h
title: Chronic heat tolerance reveals overestimated thermal safety margins and increased vulnerability in marine fish populations

description: Predicting vulnerability to global warming remains an elusive goal in
 thermal biology. In marine fishes, ongoing changes in distribution
 contrast with their apparent capacity to tolerate temperatures from 5 ºC
 up to 25 ºC higher than current conditions. Employing a dataset of 786
 upper critical temperatures across 213 species and recent theoretical
 developments, we provide conclusive evidence that these so-called ‘thermal
 safety margins’ overestimate the resilience to warming and that most
 species inhabit thermal conditions approaching their physiological
 tolerance limit. This result holds across latitudes and based on
 historical records, several populations have encountered stressful
 temperatures in the recent past. While warming tolerance remains similar
 across geographic regions, behavioral responses are constrained at low
 latitudes as distribution shifts required to encounter cooler waters are
 disproportionally higher in the tropics. Overall, our results illustrate
 how thermotolerance measures can be extrapolated to the field and used to
 quantify vulnerability to warming.
description: We compiled heat tolerance data for marine fish species started
 by retrieving information in previous published reviews on the subject and
 combined the original sources from these reviews with more recent
 published references found with a Boolean search in ISI Web of Science. We
 used Engauge Digitizer software (http://markummitchell.github.io/engauge-digitizer) to retrieve data from published figures when the heat tolerance values were not available in the main text or as supplementary information. From the original references, we also compiled the geographic location where the populations were collected and details on the experimental protocol described in each study to estimate the duration of each assay. With geographical location, we estimated the maximum and minimum monthly temperatures experienced by each population/species from historical data grids of sea surface temperatures between 1891 and 2020 in the COBE SST dataset provided by the NOAA (https://www.psl.noaa.gov/data/gridded/data.cobe.html). We also estimate the maximum annual monthly temperature variation across all ocean. We also use the data base of Coutant (1972) for fish measured in static assays to standardize the values ​​of tolerance at comparable temporal windows (see methods of the main text). Coutant, C. C. (1972). Water quality criteria. A report of the committee on water quality criteria. text and Appendix II-C, 410-419. Available at<br>https://www3.epa.gov/region1/npdes/merrimackstation/pdfs/ar/AR-166.pdf <br>(accessed on 23 January 2024).
description: # Data for: Chronic heat tolerance reveals overestimated thermal safety
 margins and increased vulnerability in marine fish populations Authors:
 Molina AN, García-Huidobro RM, Rezende EL & Carter MJ Main Folder: ###
 (1) Fish\_heat\_tolerance.R (Zenodo - Software) R script required to
 replicate all analyses and figures. ### (2) Fish\_limits\_historical.R
 (Zenodo - Software) R script required to obtain Historical_tmax.txt and
 Historical_tmin.txt. ### (3) fish\_data.xlsx. heat tolerance database in
 fish compiled by us. variables * phylum: taxonomic phylum * class:
 taxonomic class * order: taxonomic class * family: taxonomic family *
 genus: taxonomic genus * species: scientific name * sp_phylo: scientific
 name in the phylogeny (for those species that were absent in the
 phylogeny, we put here congeneric species or the closest taxonomic group
 available to obtain their location in the phylogeny) * iucn: conservation
 status according to the iucn ([http://www.iucn.org](http://www.iucn.org))
 * stage: ontogenetic stage * body.mass_g: body mass (g) * tkomax: upper
 critical temperature (ºC) - endpoint value * time: exposure time (minutes)
 * t_acc: acclimation temperature in the laboratory (ºC) * t0: starting
 temperature in ramping assays (=0 if is static) (ºC) * ramp: heating rate
 (ºC/min) * abs_latitude: absolute latitude * lat: latitude (decimals) *
 long: longitude (decimals) * dataset: review to which the data belong, NA
 when the value was obtained from an independent search * ct.ref: specific
 reference where the data comes from * lme: Large Marine Ecosystems The
 Excel rows where there is no data means that this value was not available
 in the original article. The R script is programmed to control all these
 things and make data analysis and visualization efficient. ### (4)
 Dataset\_Coutant.xlsx. heat tolerance database in fish compiled by Coutant
 (1972) in Appendix ll-C
 ([https://www3.epa.gov/region1/npdes/merrimackstation/pdfs/ar/AR-166.pdf](https://www3.epa.gov/region1/npdes/merrimackstation/pdfs/ar/AR-166.pdf)). Note that the database starts at column 8, for this reason the R script skips the first 7 rows before starting the analysis ("read_excel("Dataset_Coutant.xlsx", sheet = "Sheet1",skip=7)"). The merged cells that are presented in the headers are present for a better visualization of the data in row 6, but this does not affect the analysis because they are eliminated in the script that analyzes the data. The Excel rows where there is no data means that this value was not available in the original article. Empty cells in a column correspond to data that was not available and that this comes from the original source The R script is programmed to control all these things and make data analysis and visualization efficient. variables * sp: scientific name * sp_phylo: scientific name separated by a "_" * stage_original: state of development * length_original: length of the organism (the units are different and these should be reviewed in Appendix ll-C of Coutant 1972) * weight_original: weight of the organism (the units are different and these should be reviewed in Appendix ll-C of Coutant 1972) * sex: sex of the organism * location: location of the organism * order: taxonomic order * family: taxonomic family * class: taxonomic class * reference: source reference * extreme: whether the upper limit is Upper or Lower * temp_acc: acclimation temperature * time_acc: acclimation time (units may vary and are noted in Excel) * a: intercept of relation between logtime and temperature (see main Text) * b: slope of relation between logtime and temperature (see main Text) * N: number of measurement temperatures * r: correlation coefficient * upper_range: highest measurement temperature * lower_range: lowest measurement temperature * ld50: lethal temperature for 50% mortality * lethal_thr: critical temperature at which an organism cannot survive due to thermal exposure * page: page from which the data was taken from Appendix ll-C of Coutant 1972 * fish: This answers the question of whether the organism is a ray-finned fish (yes or no). * lat: latitude º * lon: longitude º * ott.id: species code to be able to use Open Tree of Life \**** These data are from Coutant (1972) ### (5) Historical\_tmax.txt historical temperatures (monthly means for the warmest month) columns: from tmax1891, tmax1892, tmax1893, tmax1894.... to tmax2020 (n=30) each column has 786 values, one for each heat tolerance value To get this you must run the script: Fish_limits_historical.R ### (6) Historical\_tmin.txt historical temperatures (monthly means for the coldest month) columns: from tmin1891, tmin1892, tmin1893, tmin1894.... to tmin2020 (n=30) each column have 786 values, one for each heat tolerance value To get this you must run the script: Fish_limits_historical.R ### (7) Fish\_phylogeny\_species.nex phylogeny with all the studied species. ### (8) sst.mon.mean.nc historical data grids of sea surface temperatures between 1891 and 2020 in the COBE SST ([https://www.psl.noaa.gov/data/gridded/data.cobe.html](https://www.psl.noaa.gov/data/gridded/data.cobe.html)) ### (9) temperature\_global\_data.txt historical temperatures (monthly means for the warmest month) for all the ocean columns: from tmin1891, tmin1892, tmin1893, tmin1894.... to tmin2020 (n=30) raws: each coordinate in the ocean (combination of latitude and longitude) **References:** * Coutant, C. C. (1972). Water quality criteria. A report of the committee on water quality criteria. text and Appendix II-C, 410-419. Available at [https://www3.epa.gov/region1/npdes/merrimackstation/pdfs/ar/AR-166.pdf](https://www3.epa.gov/region1/npdes/merrimackstation/pdfs/ar/AR-166.pdf) (accessed on 23 January 2024).