Bleaching prevalence and extent during the 2022 bleaching event on the central Great Barrier Reef (EcoRRAP)

Understanding variation in coral bleaching responses across environmental gradients, taxa, and colony sizes is important to predict changes in community composition with climate change. Our aim was to quantify how bleaching severity varied with water velocity, cross shelf gradient, degree heating weeks (DHWs), surface complexity, depth, taxa, and colony size during the 2022 mild bleaching event on the central Great Barrier Reef (GBR).During March and April 2022, we surveyed > 7000m2 of reef substrate using photogrammetry, and scored the bleaching severity of more than 5000 coral colonies belonging to 13 taxa.A series of generalised linear mixed effects models were fitted to quantify the relationship between bleaching severity and the key biological and environmental factors. The data includes the following variables: Reef- unique identification for each reef: OCCH - Chicken Reef, OCDA- Davies Reef, OCLB- Little Broadhurst Reef, PA -Palm Islands Exposure- prevailing wind exposure: BA- back (leeward, protected) FR- front (windward, exposed) FL- flank (intermediate exposure) LA- lagoon Zone - depth zone (S = shallow, 3-8 m; D = deep, 9-15 m) Site - unique identification for each site (replicate sites per reef). Labelled as: Reef_Exposure/ReplicateNumber/Zone Plot - unique identification for each 12x6m plot (four replicates per site). Labelled as: Site_PlotReplicate TL_id - colony identification number (unique for each colony within plot) Taxa - taxonomic idenfitication of each colony: Adgt - Acropora digitate spp., Pmas - Porites massive spp., Pver - Pocillopora verrucosa, Acor - Acropora corymbose spp., Lobo_sp - Lobophyllia spp., Menc- Montipora encrusting spp., Gspp- Goniastrea spp., Spis - Stylophora pistillata, Shys- Seriatopora hystrix, Abra- Acropora branching spp., Pdam - Pocillopora damicornis, Plat - Platygyra spp., Atab - Acropora tabular spp. Bleaching - bleaching score: 1 - no bleaching, 2 - 1-50% of the colony area was bleached, 3- 51-95% of the colony area was bleached, 4 - 96-100% of the colony area was bleached, 5 - partial mortality, 6- whole colony mortality. lat - site latitude long - site longitude ubedmean = horizontal water velocity at the bed (m/s). Extracted from Callaghan et al 2023- https://espace.library.uq.edu.au/view/UQ:8246441 . Date_2022 = date of the initial survey in January 2022 Date_bleaching = date of the bleaching survey in March - April 2022 DHW - degree heating weeks (°C-weeks). Extracted from NOAA's daily 5km satellite dervied estimates: https://coralreefwatch.noaa.gov/product/5km/index_5km_dhw.php. rugosity_plane: rugosity at the site, extracted from the reconstructed 3D models fd_fugosity_plane: fractal dimension at the site, extracted from the reconstructed 3D models slope: the slope of the site (in degrees), extracted from the reconstructed 3D models Cross_shelf: cross shelf position (inshore or offshore) log_area : colony area in (m2) (log10)

探究环境梯度、珊瑚类群以及群体大小对珊瑚白化响应的差异，对于预测气候变化下珊瑚群落组成的变化具有重要意义。本研究旨在量化2022年澳大利亚中部大堡礁（Great Barrier Reef, GBR）轻度白化事件中，白化严重程度随水流速度、陆架跨梯度、累计热周（degree heating weeks, DHWs）、表面复杂度、水深、珊瑚类群以及群体大小的变化规律。2022年3-4月，研究团队采用摄影测量法对超过7000平方米的礁体基底开展调查，并对隶属于13个类群的5000余个珊瑚群体的白化严重程度进行了评分。本研究构建了一系列广义线性混合效应模型，以量化白化严重程度与关键生物、环境因子之间的关联。本数据集包含以下变量：
1. Reef：礁体唯一标识，具体对应如下：OCCH：鸡礁（Chicken Reef），OCDA：戴维斯礁（Davies Reef），OCLB：小布罗德赫斯特礁（Little Broadhurst Reef），PA：棕榈群岛（Palm Islands）
2. Exposure：主导风暴露等级，分为：BA：背风区（背风，受保护），FR：迎风区（迎风，受强扰动），FL：侧翼区（中等暴露程度），LA：潟湖区
3. Zone：水深分区，其中S代表浅水区（3-8米），D代表深水区（9-15米）
4. Site：每个样点的唯一标识（每个礁体设置多个重复样点），命名格式为：礁体_暴露等级/重复样点编号/水深分区
5. Plot：每个12×6米样方的唯一标识（每个样点设置4个重复样方），命名格式为：样点_样方重复编号
6. TL_id：珊瑚群体编号（每个样方内的群体编号唯一）
7. Taxa：珊瑚群体的类群标识，具体如下：Adgt：指状轴孔珊瑚类群（Acropora digitate spp.），Pmas：块状微孔珊瑚类群（Porites massive spp.），Pver：疣状杯形珊瑚（Pocillopora verrucosa），Acor：伞房状轴孔珊瑚类群（Acropora corymbose spp.），Lobo_sp：叶状珊瑚属类群（Lobophyllia spp.），Menc：包壳状板孔珊瑚类群（Montipora encrusting spp.），Gspp：角菊珊瑚属类群（Goniastrea spp.），Spis：指状鹿角珊瑚（Stylophora pistillata），Shys：排孔珊瑚（Seriatopora hystrix），Abra：分枝状轴孔珊瑚类群（Acropora branching spp.），Pdam：鹿角杯形珊瑚（Pocillopora damicornis），Plat：扁脑珊瑚属类群（Platygyra spp.），Atab：桌状轴孔珊瑚类群（Acropora tabular spp.）
8. Bleaching：白化严重程度评分，评分标准如下：1：无白化，2：珊瑚群体1%-50%的区域发生白化，3：51%-95%的区域发生白化，4：96%-100%的区域发生白化，5：部分群体死亡，6：整个群体死亡
9. lat：样点纬度
10. long：样点经度
11. ubedmean：礁床处的水平水流速度（单位：米/秒），数据源自Callaghan等人2023年的研究：https://espace.library.uq.edu.au/view/UQ:8246441
12. Date_2022：2022年1月初始调查的日期
13. Date_bleaching：2022年3-4月白化调查的日期
14. DHW（degree heating weeks）：累计热周（单位：℃·周），数据源自美国国家海洋和大气管理局（NOAA）每日5公里分辨率卫星反演结果：https://coralreefwatch.noaa.gov/product/5km/index_5km_dhw.php
15. rugosity_plane：样点表面粗糙度，数据源自重建的三维模型
16. fd_fugosity_plane：样点分形维数，数据源自重建的三维模型
17. slope：样点地形坡度（单位：度），数据源自重建的三维模型
18. Cross_shelf：陆架跨向位置（近岸或远岸）
19. log_area：以log10转换的珊瑚群体面积（单位：平方米）