Benthic Surveys in Faga'alu, American Samoa: benthic images collected during belt transect surveys in 2020 (NCEI Accession 0259389)

The benthic images provided here are part of the CRCP-funded project aimed at establishing baseline Rapid Ecological Assessment (REA) surveys for coral reef benthic cover and composition at Faga'alu Bay, Tutuila, American Samoa. In 2020, the survey implemented a one -stage stratified random sampling (StRS) design to assess the Faga'alu benthic coral reef community. 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), reef zone (i.e., backreef and forereef), 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.

In 2020, thirty images were collected along one, haphazardly laid, 30-m transects. Still photographs were collected to record the benthic community composition at predetermined points along belt transect with a high-resolution digital camera mounted on a pole. Photographs were taken every 1 m from the 1 m to the 30 m mark. This work generates 30 photographs per site, which are later analyzed by ESD staff and partners using the computer program CoralNet. This analysis is the basis for estimating benthic cover and composition at each site, which is accessible on a separate NCEI accession.

Survey protocols followed the National Coral Reef Monitoring Program methodologies historically implemented by NOAA's Ecosystem Sciences Division.