In situ temperature measurements at St. John, VI, and Mo'orea LTER sites, 1989-2019

<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><p><strong>概述</strong></p> <p>莫雷阿岛与圣约翰岛的珊瑚礁已被持续监测数十年，过往基于该监测工作发表的研究成果，为完整解读本研究结果提供了生态学背景支撑。本数据集呈现了莫雷阿岛及圣约翰岛三类生境中所有类群合并统计的珊瑚覆盖度数据，这些数据源自2005至2019年间每年在固定监测点位采集的照片样方（photoquadrats，0.5 × 0.5 m）。具体而言，莫雷阿岛的三类生境采样覆盖全岛6个站点：礁前带分别在10米与17米水深处各设40个照片样方/站点；礁后带则以每个礁块（bommie）为单位布设20个照片样方，每个站点设5个礁块。2005年，研究人员在各站点礁前带的10米与17米水深处，沿约50米的样带随机布设照片样方，后续采样均沿用该固定点位。每年采样时，研究人员会在每个礁块沿四个方位轴设置的5米样带上随机布设5个照片样方。圣约翰岛的裙礁采样点位设置在7-9米水深处，共设6个站点，每年沿每条40米样带随机布设40个照片样方。</p> <p>本研究采用CoralNet软件对礁前带及圣约翰岛的照片样方进行分析，具体操作为在每张图像上随机放置200个标记点，识别每个标记点下方的底质类型。礁后带的照片样方则采用较低分辨率的分析方式：识别每个照片样方内25个子方格中占主导地位的底质类型（即分辨率为4%）。本数据集以站点为重复单元，呈现合并统计所有类群的石珊瑚（scleractinians）覆盖度，并以年度平均覆盖度开展与同期珊瑚附殖量的相关性检验。</p> <p>为验证支撑本研究的各项假说，研究团队于2005至2019年间通过布设附着基瓦片（settlement tiles）对莫雷阿岛与圣约翰岛的珊瑚附殖量进行测量，并使用温度记录器（loggers）监测海水温度。由于两项采样计划最初的设计目的不同，两区域附着基瓦片的浸没时长存在细微差异。</p>