Depth variation in benthic community response to repeated marine heatwaves on remote Central Indian Ocean reefs

Coral reefs are increasingly impacted by climate-induced warming events. However, there is limited empirical evidence on the variation in the response of shallow coral reef communities to thermal stress across depth. Here we assess depth-dependent changes in coral reef benthic communities following successive marine heatwaves from 2015 to 2017 across a 5–25 m depth gradient in the remote Chagos Archipelago, Central Indian Ocean. Our analyses show an overall decline in hard and soft coral cover and an increase in crustose coralline algae, sponge, and reef pavement following successive marine heatwaves on the remote reef system. Our findings indicate that the changes in benthic communities in response to elevated seawater temperatures varied across depth. We found greater changes in benthic group cover at shallow depths (5–15 m) compared to deeper zones (15–25 m). The loss of hard coral cover was better predicted by initial thermal stress, whilst the loss of soft coral was associated with..., Study Sites
The Chagos Archipelago is a remote archipelago located in the Central Indian Ocean. Situated at the southern end of the Laccadives-Maldives-Chagos ridge, it covers a total area of 640,000 km2 and consists of five islanded atolls. The archipelago has been uninhabited since the early 1970s, except for the US military base on the southern atoll, Diego Garcia (81). Benthic community data were collected with repeat sampling, in March–April 2013/2014 (before) and 2018/2019 (after) following successive severe marine heatwaves in 2015–2017. The peaks of marine heatwave events occurred between May–June 2015 (4.2 ± 0.4 – 6.1 ± 0.3 °C-weeks) and April–June 2016 (12.1 ± 0.1 – 15.8 ± 0.1 °C-weeks) (Figure S1). Surveys in each period were carried out at 16 sites on forereef slopes across four atolls: Peros Banhos (PB), Salomon (SA), Great Chagos Bank (GCB), and Egmont (EG) (Figure 1), and conducted at four depth zones: 5–10 m, 10–15 m, 15–20 m, and 20–25 m. For ease of interpretation, sha..., All data analyses were performed using R 3.5.1., # Title: Depth variation in benthic community response to repeated marine heatwaves on remote Central Indian Ocean reefs

This is a brief summary of all the datasets used to produce the plots and results for the above paper

Description of data and structure

1. Percentage cover data of all benthic groups (categories): raw.broadcat.csv
Dataset content:
* Categories - refer to benthic groups surveyed: hard coral, soft coral, crustose coralline algae (CCA), sponge and reef pavement
* Photo.Name - refer to each digital photo-quadrat
* Year - 2013/2014 refers to data collected before the 2015-2017 marine heatwaves
* 2018/2019 refer to data collected after the 2015-2017 marine heatwaves
* Atoll - where data was collected EG: Egmont, GCB: Great Chagos Bank, SA: Salomon, PB: Peros Banhos
* Site - refer to sites around each atoll where data was collected
* Heatwaves - post refers to 2018/2019 when data was collected after 2015-2017 marine heatwaves...

# 论文标题：中印度洋偏远礁体底栖生物群落对重复海洋热浪的深度响应差异

珊瑚礁正日益受到气候诱导升温事件的影响。然而，目前关于浅海珊瑚礁群落在不同深度下对热胁迫响应的差异的实证研究仍较为匮乏。

本研究针对中印度洋偏远的查戈斯群岛（Chagos Archipelago）5至25米的深度梯度带，评估了2015至2017年连续海洋热浪发生后，珊瑚礁底栖生物群落的深度依赖性变化。分析结果显示，该偏远礁体系统经历连续海洋热浪后，硬珊瑚与软珊瑚的盖度整体下降，而结壳珊瑚藻（crustose coralline algae, CCA）、海绵及礁坪的盖度则有所上升。研究表明，底栖生物群落对海水温度升高的响应变化随深度而异：相较于15至25米的深水区，浅水区（5至15米）的底栖类群盖度变化幅度更大。硬珊瑚盖度的损失可通过初始热胁迫更好地预测，而软珊瑚盖度的损失则与……相关。

## 研究地点
查戈斯群岛地处中印度洋，是一处偏远群岛。其位于拉克代夫-马尔代夫-查戈斯海岭的南端，总面积达64万平方千米，由5个环礁岛群组成。自20世纪70年代初以来，该群岛除南部环礁迪戈加西亚（Diego Garcia）上的美国军事基地外，其余区域均无人居住（参考文献81）。

底栖生物群落数据通过重复采样获取，分别于2015至2017年连续严重海洋热浪发生前的2013/2014年3-4月，以及热浪发生后的2018/2019年完成采集。海洋热浪峰值分别出现在2015年5-6月（4.2±0.4 至 6.1±0.3 摄氏度·周）与2016年4-6月（12.1±0.1 至 15.8±0.1 摄氏度·周）（补充图S1）。每个采样时段的调查均在4个环礁的礁前斜坡上的16个样点开展，这4个环礁分别为佩罗斯巴尼奥斯（Peros Banhos, PB）、所罗门（Salomon, SA）、查戈斯大滩（Great Chagos Bank, GCB）与埃格蒙特（Egmont, EG）（图1），采样覆盖4个深度带：5-10米、10-15米、15-20米及20-25米。为便于解读，本研究对部分内容进行了简写……

所有数据分析均通过R 3.5.1软件完成。

本文件为上述论文中用于生成图表与结果的全部数据集的简要说明。

### 数据集与结构说明
1. 所有底栖类群盖度数据：raw.broadcat.csv
数据集内容：
* 类别：指调查涵盖的底栖类群，包括硬珊瑚、软珊瑚、结壳珊瑚藻（crustose coralline algae, CCA）、海绵与礁坪
* Photo.Name：对应每张数码样方照片的编号
* 年份：2013/2014代表2015-2017年海洋热浪发生前采集的数据；2018/2019代表热浪发生后采集的数据
* 环礁：数据采集所在的环礁，其中EG为埃格蒙特，GCB为查戈斯大滩，SA为所罗门，PB为佩罗斯巴尼奥斯
* 样点：指各环礁周边的数据采集样点
* 热浪状态：post代表2018/2019年，即2015-2017年海洋热浪发生后的采样时段……