Coral recruitment locations on tiles (top, bottom, sides) at St. John, VI, and Mo'orea LTER sites, 1985-2020, for Edmunds (L&O, 2020)

<p><strong>Overview</strong></p>

<p>The reefs in Mo'orea and St. John have been monitored for decades, and recent publications from these efforts provide the ecological background to fully interpret the present results. Coral cover (pooled among taxa) for all three habitats in Mo'orea, as well as St. John, are presented, with these data originating from photoquadrats (0.5 × 0.5 m) that have been recorded annually at permanent locations from 2005 to 2019. In brief, in Mo'orea, the three habitats were sampled at six sites around the island, with 40 photoquadrats/site at 10-m and 17-m depth on the fore reef, and 20 photoquadrats/bommie, and five bommies/site, in the back reef. In 2005, photoquadrats were randomly positioned along a ~ 50 m transect at 10-m and 17-m depth at each site on the fore reef, and thereafter were sampled in the same positions. Five photoquadrats were randomly positioned along four, 5-m transects along cardinal axes at each bommie every year. In St. John, the fringing reefs (at 7-9-m depth) were sampled at six sites, with 40 photoquadrats randomly positioned every year along a single 40-m transect at each site.</p>

<p>Photoquadrats from the fore reef and from St. John were analyzed using CoralNet Software, with 200 dots randomly located on each image, and the substratum beneath each dot identified. The photoquadrats in the back reef were analyzed with a coarser resolution in which the dominant substratum is each of 25 sub-squares in each photoquadrat was identified (i.e., providing 4% resolution). The cover of scleractinians (pooled among taxa) is presented using sites as replicates, and mean cover by year is used in tests of association with concurrent coral recruitment.</p>

<p>To test the hypotheses guiding the present study, coral recruitment was measured in Mo'orea and St. John using settlement tiles deployed from 2005 to 2019, and loggers were used to measure temperature. The immersion times of settlement tiles slightly differed between regions because the two sampling programs originally were designed for different purposes.</p>

**概览**

莫雷阿岛（Mo'orea）与圣约翰岛（St. John）的珊瑚礁已被长期监测数十年，过往监测工作产出的最新研究成果可为完整解读本研究结果提供生态学背景支撑。本研究呈现了莫雷阿岛及圣约翰岛三处生境的珊瑚盖度（按类群合并统计），相关数据来自2005年至2019年间每年在固定点位记录的样方照片（photoquadrat，0.5×0.5米）。简要而言，莫雷阿岛的三处生境在全岛6个点位开展采样：礁前带设置10米与17米水深点位，每个点位布设40张样方照片；礁后带则以珊瑚礁块（bommie）为单元，每个礁块布设20张样方照片，每个点位设置5个礁块。2005年时，礁前带每个点位的10米与17米水深处，沿约50米样带随机布设样方照片，后续年份均在相同位置采样。每年采样时，每个礁块沿四个主方位轴设置4条5米样带，每条样带随机布设5张样方照片。圣约翰岛的岸礁（fringing reef，水深7-9米）在6个点位开展采样，每个点位沿单条40米样带每年随机布设40张样方照片。

礁前带与圣约翰岛的样方照片采用CoralNet软件（CoralNet）进行分析：每张图像随机叠加200个采样点，识别每个采样点下方的底质（substratum）。礁后带的样方照片则采用更低分辨率的分析方式，对每张样方照片内的25个亚方格逐一识别其优势底质（即分辨率为4%）。本研究呈现的石珊瑚（scleractinian）盖度按类群合并统计，以点位作为重复单元；年度平均盖度则用于与同期珊瑚幼体补充量的相关性检验。

为验证本研究的核心假说，研究团队于2005年至2019年间通过投放幼体附着盘（settlement tile）对莫雷阿岛与圣约翰岛的珊瑚幼体补充量进行测定，并利用温度记录仪（logger）监测水温。由于两处采样计划最初的设计目标存在差异，幼体附着盘的浸没时长在两个区域间存在细微差异。