Coral community structure at pooled random sites between Cabritte Horn and White Point in St. John before and after five hurricanes from 1988–2017

<p>The shallow reefs (≤ 14-m depth) of St. John have been subjects of time-series analyses since December 1987. Study plots first were established at 9-m depth at Yawzi Point, and at 14-m depth at Tektite, both of which provide examples of reefs dominated by <em>Orbicella annularis</em>. The initial sampling evaluated the impacts of coral bleaching in 1987, and each site consisted of three, 10-m transects placed at a constant depth, parallel to one another (and 5-m apart), and permanently marked. Ten contiguous photoquadrats (1 × 1 m) have been recorded along each transect annually, and here results from 1988 (March) and 1989 (April and October) are used to evaluate the effects of Hurricane Hugo, from 1995 (May) and 1996 (May) to evaluate the effects of Hurricanes Luis and Marilyn, and from 2017 (July and November) to evaluate the effects of Hurricanes Irma and Maria. The damage from Hurricane Hugo at Yawzi Point was extensive, and to capture this spatial scale of damage, the analysis was expanded with four, unmarked 20-m transects. In 1989, these transects were recorded using Hi-8 video (Sony Corporation), but starting in 1992, they were recorded as contiguous photoquadrats using underwater cameras. Surveys of these 20-m transects from 1989 (October), 1995 (May), 1996 (May), and 2017 (July and November) are used here to expand the spatial scale of the present analysis.</p>

自1987年12月起，圣约翰岛（St. John）的浅礁（水深≤14米）就已成为时间序列分析的研究对象。首个研究样地分别设立于Yawzi Point的9米水深处与Tektite的14米水深处，两处均为以*Orbicella annularis*（环纹扁脑珊瑚）为优势种的礁体典范。初始采样于1987年开展，旨在评估珊瑚白化的影响；每个样地设置3条固定水深的10米样线，彼此平行且间距5米，并做永久标记。每年沿每条样线记录10个连续的1×1米摄影样方（photoquadrats）；本研究使用1988年3月、1989年4月与10月的调查数据评估雨果飓风（Hurricane Hugo）的影响，1995年5月、1996年5月的数据评估路易斯飓风与玛丽莲飓风（Hurricanes Luis and Marilyn）的影响，2017年7月与11月的数据则用于评估艾尔玛飓风与玛丽亚飓风（Hurricanes Irma and Maria）的影响。雨果飓风对Yawzi Point礁体造成了大面积破坏，为覆盖该破坏的空间尺度，研究新增了4条未做标记的20米样线。1989年，这些样线采用Hi-8摄像机（索尼公司（Sony Corporation））进行录制；自1992年起，则改用水下相机拍摄连续摄影样方。本研究使用1989年10月、1995年5月、1996年5月以及2017年7月与11月对这些20米样线的调查数据，以拓展本次分析的空间尺度。