Global warming transforms coral reef assemblages

Brief description

This dataset supports the 2018 Nature publication by Terry Hughes and 15 co-authors, entitled 'Global warming transforms coral reef assemblages'. It is comprised of three separate excel files:

(1) Aerial Survey Data - which gives aerial scores of bleaching severity for 1156 coral reefs on the Great Barrier Reef in March/April 2016.

(2) In Water Survey Data - which gives data for instantaneous and longer-term mortality (March 2016 to November 2016) of corals, and associated heat stress for 63 reefs on the Great Barrier Reef.

(3) Taxonomic Data - which gives benthic cover data for 15 individual taxa at two time points: (a) during the peak of the 2016 mass coral bleaching event (March 2016) and (b) eight months later (November 2016).

Full description

This dataset supports the 2018 Nature publication by Terry Hughes and 15 co-authors, entitled 'Global warming transforms coral reef assemblages'. It is comprised of three separate excel files:

(1) Aerial Survey Data

Aerial surveys were conducted in March and April 2016 to measure the geographic extent and severity of bleaching on the Great Barrier Reef. Each of 1,156 individual reefs was scored into one of five bleaching categories: (0) less than 1% of corals bleached, (1) 1-10%, (2) 10-30%, (3) 30-60%, and (4) more than 60% of corals bleached. The accuracy of the aerial scores was ground-truthed by measuring the extent of bleaching underwater on 104 reefs, also during March/April 2016. The aerial surveys were conducted throughout the Great Barrier Reef Marine Park and Torres Strait between Australia and Papua New Guinea, from the coast of Queensland to the outermost reefs, and along the entire Reef from latitudes 9.5-23.5°S.

The aerial bleaching scores were subsequently converted into mortality estimates using a calibration curve based on underwater measurements of coral losses.

The dataset contains the following information:

Reef identification (ReefID, ReefName, Longitude, Latitude)

BleachingCategory (categories described above ranging from 0 – 5)

ChangeCover (%) (the estimate of mortality for a giving bleaching category, described above)

(2) In Water Survey Data

At the same time as the aerial surveys, in-water surveys of 63 reefs were conducted to assess levels of coral cover and initial mortality of different taxa due to heat stress. On each reef, the extent of bleaching and mortality on individual coral colonies was measured at two sites using five 10 x 1 m belt transects placed on the reef crest at a depth of 2 m. Longer-term coral loss was measured at the same 63 reefs in October and November 2016, eight months after the initial in-water surveys.

Heat stress on the Great Barrier Reef in 2016 was quantified at 5 km resolution, using the NOAA Coral Reef Watch version 3 Degree Heating Week (DHW) metric.

The dataset contains the following information:

ReefID

Heat stress (in degree Centigrade weeks, see above description)

InstantMortality (the percentage of colonies that died instantaneously during the mass bleaching event)

PercentBleached (%) (the percentage of colonies that were bleached during the mass bleaching event)

ChangeInCover (the difference between final coral cover and initial coral cover (including recently dead coral), both values were log10-transformed prior to calculating the change in cover)

DeltaMDS (the before-after shift in taxonomic composition for a given reef space based on a non-metric multi-dimensional scaling analysis of coral assemblages, see below for description)

(3) Taxonomic Data

The in-water surveys described above, were conducted at a fine taxonomic resolution. To include all species, the majority of which are too rare to analyse individually, we pooled them into 15 ecologically cohesive groups depending on their morphology, life history, and taxonomy. Three of the 15 are ubiquitous species or species complexes: Pocillopora damicornis, Seriatopora hystrix, and Stylophora pistillata. In each of the multi-species groups, the dominant species or genera on reef crests were: Other Acropora (A. gemmifera, A. humilis, A. loripes, A. nasuta, A. secale, A. tenuis, A. valida); Favids (i.e. species and genera from the formerly recognized Family Faviidae - Cyphastrea, Favia, Favites, Goniastrea, Leptastrea, Montastrea, Platygyra); Mussidae (Lobophyllia, Symphyllia); Isopora (I. palifera, I. cuneata); Other Pocillopora (P. meandrina, P. verrucosa); Other sessile animals (sponges, tunicates, molluscs); Porites (P. annae, P. lobata);  Montipora (M. foliosa, M. grisea, M. hispida, M. montasteriata, M. tuberculosa); Staghorn Acropora (A. florida, A. intermedia, A. microphthalma, A. muricata, A. robusta); Soft Corals (alcyonaceans, zooanthids); and Tabular Acropora (A. cytherea, A. hyacinthus, A. anthocercis).

The coral cover for each of the 15 taxonomic categories has been provided for the initial surveys in March and April 2016 and the later surveys in October and November 2016. These data were used to generate the nMDS analysis discussed above. The shift in composition is measured as the Euclidean distance between the initial and final nMDS values for each location.

The dataset contains the following information:

ReefID as rows

Taxonomic Category (e.g. Isopora) as columns

Notes

This dataset is available as 3 spreadsheets in MS Excel (.xlsx) and Open Document formats (.ods)