Data Management Plan

Jurisdictional managers have expressed concerns that nutrients from the village of Vatia, Tutuila, American Samoa, are having an adverse effect on the adjacent coral reef ecosystem. Excess nutrient loads promote increases in algal growth that can have deleterious effects on corals, such as benthic algae outcompeting and overgrowing corals. Nitrogen and phosphorus can also directly impact corals by lowering fertilization success, and reducing both photosynthesis and calcification rates. Land-based contributions of nutrients come from a variety of sources; in Vatia the most likely sources are poor wastewater management from piggeries and septic systems.

NOAA scientists conducted benthic surveys to establish a baseline against which to compare changes in the algal and coral assemblages in response to land-based sources of pollution, including nutrient fluxes.

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) in Vatia Bay American Samoa in 2015, and 2020. 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 2015, the survey implemented a two-stage stratified random sampling (StRS) design to assess the Vatia coral reef community, and a one-stage StRS design in 2020. 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.

Vatia Bay, Tutuila, American Samoa

Lineage Statement:
The data described here were collected via belt transect surveys of coral demography (adult and juvenile corals) by the NOAA Coral Reef Ecosystem Program (CREP) following the same protocol to that established by the NOAA National Coral Reef Monitoring Program (NCRMP).

Process Steps:

• Biological surveys implemented a modified stratified random sampling design to assess the survey domain which encompassed the hard-bottom reef habitat from 0 to 18 m in depth within Vatia Bay. Based on the geomorphology of the reef, the stratification scheme combined two depth categories (shallow: 0–6 m and mid-depth: 6–18 m) and two cardinal positions (north and south) into four distinct strata: i.e., mid-depth north, mid-depth south, shallow north, and shallow south). A digital map of the survey domain was overlaid with a 30 m × 30 m grid designating potential survey sites in all four strata. Sampling effort was allocated relative to strata area and survey sites were randomly selected within each stratum Belt-transects were the focal point of the biological surveys. Coral community composition was assessed within a number of 1.0 m × 2.5 m segments located at the 0–2.5 m, 5.0–7.5 m, 10–12.5 m, 15–17.5 m mark along each transect; bottom-time permitting, covering a total area ranging 5–10 m2 per transect. Over time, protocols were adjusted to increase efficiency such that two, 18-m transects in 2015, and one 18-m transect in 2020. Within segments, all adult coral colonies (≥5 cm maximum diameter) whose center fell within 0.5 m on either side of the transect line were identified to the genus-level and measured for size (maximum diameter to nearest cm). Juvenile coral colonies (<5 cm), distinguished by the presence of a distinct tissue and skeletal boundary (not a remnant of a larger colony), were surveyed within three 1.0 m × 1.0 m segments at the 0–1.0 m, 5.0–6.0 m, and 10.0–11.0 m mark of each transect (covering 3 m2 per transect). Juvenile colonies were identified to genus and measured for size (maximum diameter to nearest 5 mm). For the estimation of benthic cover, still photographs were collected using the photoquadrat method at predetermined points along the transect line with a high-resolution digital camera mounted on a pole. In 2015, photographs were taken every meter from the 1-m to the 15-m mark on each of the two transects per site (n = 30) and in 2020, every meter from the 1-m to the 30-m mark along an extended belt-transect line (n = 30). Photoquadrats were analyzed implementing the computer software CoralNet. These data are documented separately. Survey protocols followed the National Coral Reef Monitoring Program methodologies historically implemented by NOAA's Ecosystem Sciences Division. (Citation: Ecosystem Sciences Division standard operating procedures: data collection for rapid ecological assessment benthic surveys)

The quality control occurred at two major stages - 1) data entry and 2) data management. Data entry quality control included both review and manual error correction steps. Data management quality control included several standard error queries followed by correction prior to ingestion into Oracle database.

Data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

NOAA IRC and NOAA Fisheries ITS resources and assets.