Virgin Islands National Park: Coral Reef: Population Dynamics: Scleractinian corals

These data are evidence of the the long-term dynamics of shallow coral reefs along
the south coast of St. John from as early as 1987. These data describe coral reef
community structure as percent cover based on the analysis of color photographs. All
of these data originate from color images of photoquadrats recorded annually
(usually in the summer) from as early as 1987. The data falls into three groups. The
two groups that are contained in this data package are (1) Tektite & Yawzi and
(2) Random sites. The juvenile coral density is packaged separately. Tektite – this is at 14 m depth on the eastern side of Great Lameshur Bay and is
the original site of the Tektite man-in-the sea project in 1969; this project marked
the birth of the Virgin Islands Ecological Research Station (later the Virgin
Islands Environmental Resource Station) that hosts the field component of the
project. The reef in this location consists of a single buttress that has remained
dominated by Montastraea anularis since the start of the research (1987). These
surveys consist of 30 photoquadrats (1 x 1 m) distributed along three, 10 m
transects. Yawzi – this is at 9 m depth and is on the western side of Great Lameshur Bay and
has been recorded photographically since 1987. This reef also started the study
period dominated by Montastraea annularis, but has degraded much more rapidly that
the Tektite site. These surveys consist of 30 photoquadrats (1 x 1 m) distributed
along three, 10 m transects. Random sites – were added in 1992 to address the concern that the original sites
(Yawzi and Tektite) were selected on “good” areas of reef and, therefore, could only
decline in condition. The Random sites were selected using random coordinates in
1992, and consist of 6 sites (at 7-9 m depth) scattered between Cabritte Point and
White Point. All lie a little shoreward of Yawzi and Tektite, and have always been
characterized by low coral cover (< 10% cover). The surveys consist of 18-40
photoquadrats (0.5 x 0.5 m; with sample size determined by the exposures on a 35 mm
cassette versus digital techniques) that are placed at random points along a
transect.

本数据集记录了圣约翰岛南海岸浅海珊瑚礁自1987年起的长期动态变化。本数据集通过彩色照片分析，以盖度百分比的形式呈现珊瑚礁群落结构特征。所有数据均源自自1987年起每年（通常于夏季）记录的样方照片（photoquadrats）彩色图像。本数据集共分为三类，本次数据包包含其中两组：(1) 特克蒂特（Tektite）与亚齐（Yawzi）样地，(2) 随机样地。幼体珊瑚密度数据单独打包发布。

特克蒂特样地：位于大拉梅舍尔湾东侧14米水深处，是1969年特克蒂特海底人类驻留项目（Tektite man-in-the sea project）的原始样地。该项目催生了维尔京群岛生态研究站（后更名为维尔京群岛环境资源站），本项目的野外工作即依托该站开展。该样地的珊瑚礁为单一礁柱，自1987年本研究启动以来，始终以环纹菊珊瑚（Montastraea annularis）为优势类群。本次调查共设置3条10米样带，沿样带分布30个1×1米的样方照片。

亚齐样地：位于大拉梅舍尔湾西侧9米水深处，自1987年起便通过摄影方式开展监测。该礁体在研究初期同样以环纹菊珊瑚（Montastraea annularis）为优势类群，但退化速度远快于特克蒂特样地。本次调查共设置3条10米样带，沿样带分布30个1×1米的样方照片。

随机样地：为弥补原始样地（亚齐与特克蒂特）仅选取礁体“优质”区域导致的监测偏差（即仅能反映礁体退化情况），研究团队于1992年增设了随机样地。随机样地通过随机坐标选取，共包含6个样点，分布于7-9米水深的卡布里特角与怀特角之间的海域，全部位于亚齐与特克蒂特样地稍靠岸的一侧，其珊瑚盖度始终较低（<10%）。本次调查沿样带随机布设18至40个0.5×0.5米的样方照片，样本量根据35毫米胶片暗盒的可拍摄张数与数码技术的拍摄能力确定。