Peyssonnelia abundance along the south shore of St. John, US Virgin Islands from surveys during 2015

<p>The abundance of the peyssonnelid algal crust was measured using 50 m video transects (recorded with a GoPro Hero 3) at 3, 5, and 7 m depth at five sites, haphazardly selected between Cabritte Horn and White Point on the south shore of St. John. Still images (n = 20 transect-1, each ~ 250 cm2) were randomly extracted and analyzed for percentage cover of peyssonnelids using a grid of 25 squares that were scored for dominance by this alga (i.e., 4% resolution).</p>本数据集通过50米视频样带法测定皮海膜属藻壳（peyssonnelid algal crust）的丰度：在圣约翰南岸的卡布里特角与怀特角之间随机选取5个采样点，分别在3 m、5 m、7 m水深处设置视频样带（采用GoPro Hero 3相机录制）。随后从每条样带中随机提取20帧静态图像（单帧面积约250 cm²），使用包含25个方格的网格对图像进行分析，以该藻类占优的方格数计算皮海膜属的盖度百分比，分辨率精度为4%。