Benthic Surveys in Vatia, American Samoa: benthic images collected during belt transect surveys from 2020-01-23 to 2020-01-29 (NCEI Accession 0259494)

This data package includes the source imagery of a benthic cover analysis for surveys performed in 2020 by the NOAA Ecosystem Sciences Division (ESD) in Vatia, American Samoa. The imagery described here was collected during belt transect surveys of coral demography by the ESD according to protocols established by the NOAA National Coral Reef Monitoring Program (NCRMP).

In 2020 the survey implemented a one-stage stratified random sampling (StRS) design. Thirty images were collected at 24 stratified randomly selected sites in Vatia Bay. The survey domain encompassed the majority of the mapped area of reef and hard bottom habitats in the 0–30 m depth range. The stratification scheme included cardinal position (i.e., north and south) and depth (i.e., shallow: >0–6 m and mid-depth: >6–18 m). Sampling effort allocation was determined based on strata area and sites randomly located within strata. The StRS design effectively reduces estimate variance through stratification using environmental covariates and by sampling more sites rather than more transects per site. Therefore, site-to-site comparisons should proceed with caution.

本数据包包含了由美国萨摩亚的瓦提亚地区美国国家海洋与大气管理局（NOAA）生态系统科学部（ESD）于2020年进行的底栖覆盖分析源图像。所述图像系由ESD根据美国国家珊瑚礁监测计划（NCRMP）制定的规范，在珊瑚人口学 belt transect 调查期间收集。2020年的调查采用了单阶段分层随机抽样（StRS）设计。在瓦提亚湾的24个分层随机选取的地点共收集了30张图像。调查区域覆盖了0-30米深度范围内大部分已测绘的礁石和硬质海底栖息地。分层方案包括主要方位（即，北和南）以及深度（即，浅水区：>0-6米和中深度区：>6-18米）。采样努力分配基于层面积以及层内随机定位的地点。StRS设计通过分层使用环境协变量以及通过增加采样地点而非在每个地点增加横断面数量，有效地降低了估计方差。因此，在站点间进行比较时应谨慎行事。