National Coral Reef Monitoring Program: Stratified Random Surveys (StRS) of Coral Demography (Adult and Juvenile Corals) across the Mariana Archipelago from 2022-05-10 to 2022-06-01 (NCEI Accession 0279491)

The data described here result from benthic coral demographic surveys for two life stages (juveniles, adults) across the Mariana archipelago from 2022-05-10 to 2022-06-01. Juvenile colony surveys include morphology and size. Adult colony surveys record morphology, colony size, partial mortality in two categories - old dead and recent dead, cause of recent dead partial mortality, and non-lesion forming condition (including bleaching and disease). Observations were repeated for internal review, and are denoted with TRANSECTNUM = 2 and REPEAT_SEGMENT_YN = -1. When using observation data for analyses, filter for TRANSECTNUM = 1.

A two-stage stratified random sampling (StRS) design was employed to survey the coral reef ecosystems throughout the U.S. Pacific regions. 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 island, reef zone, and depth in all regions, as well as habitat structure type in the Main Hawaiian Islands. Sampling effort was allocated based on strata area and sites were randomly located within strata. Sites were surveyed using belt transects to collect juvenile and adult coral colony metrics. These data provide information on juvenile and adult coral abundance (density, proportion occurrence, and total colony abundance), size distribution, partial mortality, prevalence and abundance of recent mortality and cause, prevalence of disease and bleaching, and diversity.

The StRS design effectively reduces estimate variance through stratification using environmental covariates and by sampling more sites rather than sampling more transects at a site. Therefore, site-level estimates and site to site comparisons should be used with caution.