Data from: A long-term perspective to the effects of the 2023 marine heat wave on stony corals in the Caribbean
Data files
Sep 19, 2025 version files 1.75 MB
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1_Long_Term_Temperature_1989_2025.csv
412.16 KB
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2_Monthly_temperature-by_site.csv
150.34 KB
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3_Random_Sites_coral_cover.csv
49.94 KB
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4_Random_Sites_coral_cover_genus.csv
927.16 KB
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5_Tektite_coral_cover.csv
7.38 KB
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6_Tektite_coral_cover_genus.csv
95.40 KB
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7_Yawzi_coral_cover.csv
5.76 KB
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8_Yawzi_coral_cover_genus.csv
95.36 KB
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README.md
4.77 KB
Abstract
Marine heat waves (MHW) are a leading cause of death for stony corals, and it is reasonable to expect that a record-breaking MHW would negatively impact coral communities. 2023–2024 provided a test of this assertion in St. John, US Virgin Islands, where an intense MHW brought temperatures of 30.6°C and degree-heating weeks of 23.23°C-weeks. On reefs where coral cover has been low for decades, the 2023/24 MHW did not have discernible effects on coral cover. Nonetheless, there was a trend between 2023 and 2024 for mean coral cover to decline by small absolute (≤ 3%), but large relative (13–27%) amounts, with these changes affecting multiple genera and perturbing coral assemblages, especially at 14-m depth. These trends are eclipsed by the massive changes that have affected these coral communities over the last four decades; the 2023/24 MHW was the latest in a series of disturbances transitioning these reefs to low coral cover. This MHW did not statistically depress coral cover, but it changed coral assemblages, intensifying the ecological perils of rarity, extirpation, and perhaps local extinction.
Dataset DOI: 10.5061/dryad.0vt4b8hb6
Description of the data and file structure
These data were collected in support of an analysis of the effects of the 2023 MHW on the coral reefs of St. John
Files and variables
File: 6_Tektite_coral_cover_genus.csv
Description: These data describe the percentage coral cover by genus at the Tektite Reef (14 m depth) in St. John from 2021-2024
Variables
Year = study year from 2021 to 2024
Picture ID = unique reference linking data to a photoquadrat recorded in the field
Quadrat = number of quadrats sampled each year along each transect, 1 to 10
% Cover = coral cover
Genus = coral genus
File: 2_Monthly_temperature-by_site.csv
Description: These data describe seawater temperature at 5 m depth at 6 sites between Cabritte Horn and White point (see Fig. S1)
Variables
Date = month (1 = January, etc.)
Day = day of month
Year = 10 (2010), 11 (2011) to 23 (2023).
Yawzi_Tiles = temperature (°C) at Yawzi Tile site (see Fig S1)
Tektite_Tiles = temperature (°C) at Tektite Tile site (see Fig S1)
Cabritte_Tiles = temperature (°C) at Cabritte Tile site (see Fig S1)
Little_Lam_Tiles = temperature (°C) at Little Lameshur Tile site (see Fig S1)
White_Tiles = temperature (°C) at White Point Tile site (see Fig S1)
999 = missing data
File: 3_Random_Sites_coral_cover.csv
Description: These data describe the percentage coral cover (pooled among taxa) at the five random sites in St. John from 1992-2024
Variables
Site = study site, Cabritte Horn, East Tektite, Europa Bay, West Little Lameshur, West Tektite, White Point
Quadrat = number of quadrats sampled each year from 1 up to 44
Year = study year from 1992 to 2024
% Cover = coral cover, pooled among taxa
File: 4_Random_Sites_coral_cover_genus.csv
Description: These data describe the percentage coral cover by genus at the five random sites in St. John from 2021-2024
Variables
Site = study site, Cabritte Horn, East Tektite, Europa Bay, West Little Lameshur, West Tektite, White Point
Year = study year from 2021 to 2024
Picture ID = unique reference linking data to a photoquadrat recorded in the field
% Cover = coral cover
Genus = coral genus
File: 5_Tektite_coral_cover.csv
Description: These data describe the percentage coral cover (pooled among taxa) at the Tektite Reef (14 m depth) in St. John from 1987-2024
Variables
Date = when data collected – month/day/year
Quadrat = number of quadrats sampled each year along each transect, 1 to 10
Transect = transect along which quadrats are located, 1, 2, or 3
% Cover = coral cover
nd = missing data
File: 7_Yawzi_coral_cover.csv
Description: These data describe the percentage coral cover (pooled among taxa) at the Yawzi Point reef (9 m depth) in St. John from 1987-2024
Variables
Date = when data collected – month/day/year
Picture ID = unique reference linking data to a photoquadrat recorded in the field
% Cover = coral cover, pooled among taxa
Quadrat = number of quadrats sampled each year along each transect, 1 to 10
Transect = transect along which quadrats are located, 1, 2, or 3
% Cover = coral cover
nd = missing data
File: 8_Yawzi_coral_cover_genus.csv
Description: These data describe the percentage coral cover by genus at the Yawzi Point Reef (9 m depth) in St. John from 2021-2024
Variables
Year = study year from 2021 to 2024
Picture ID = unique reference linking data to a photoquadrat recorded in the field
Quadrat = number of quadrats sampled each year along each transect, 1 to 10
% Cover = coral cover
Genus = coral genus
File: 1_Long_Term_Temperature_1989_2025.csv
Description: These data describe seawater temperature off St. John, with in situ records from Great Lameshur Bay at 9 m depth at Yawzi Point (see Fig. S1)
Instrument = logger used to collect date either (1) Ryan Tempmentor, (2) Hobo logger (U22-001), (3) SBE39, (4) nd = no data
Variables
Date = date of measurement, month/day/year
Temp°C = seawater temperature
DHW_28.43°C = degree heating weeks based on a mean monthly max (MMM) of 28.43°C, note “999” recorded where 84 consecutive daily temperature data were not available due to missing logger data
DHW_28.71°C = degree heating weeks based on a mean monthly max (MMM) of 28.71°C, note “999” recorded where 84 consecutive daily temperature data were not available due to missing logger data
NOAA DHW = degree heating weeks as published for the south coast of St. John by NOAA
999 = missing data in number columns