National Coral Reef Monitoring Program: Stratified Random Surveys (StRS) of Coral Demography (Adult and Juvenile Corals) across American Samoa in 2015 and 2018

NCRMP CORAL DEMOGRAPHIC DATA HAS NOW BEEN MERGED INTO A PACIFIC-WIDE METADATA RECORD -- PLEASE REFER TO https://www.fisheries.noaa.gov/inport/item/71550 FOR MOST UPDATED DATA.

The data described here result from benthic coral demographic surveys within belt transects of specified length and width for two life stages (juveniles and adults) across American Samoa since 2015. The data provide information on adult coral colony counts, morphology, size, partial mortality (old and recent dead), presence and causation of disease and other compromised health conditions, including bleaching. Juvenile colony surveys include morphology and size. Taxonomic identification of adult colonies is to the species level and genus level for juveniles. In 2023, some segment observations were repeated for internal quality control; to filter for non-repeated data, be certain filter for TRANSECTNUM = 1.

A two-stage stratified random sampling (StRS) design was employed to survey the coral reef ecosystems of American Samoa in 2015, and starting in 2018 a one-stage StRS design was employed. 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 (i.e., shallow: >0 - 6 m; mid-depth: > 6 -18 m; and deep: >18 - 30 m), as well as reef zone (i.e., forereef, backreef, and lagoon; backreef only at Rose Atoll and Tutuila, and lagoon only at Rose Atoll). 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-level estimates and site-to-site comparisons should proceed with caution.

The data were collected as part of the NOAA Pacific Islands Fisheries Science Center (PIFSC) and Ecosystem Sciences Division (ESD; formerly the Coral Reef Ecosystem Division) led National Coral Reef Monitoring Program (NCRMP) missions to American Samoa.