The benthic cover data described here were generated from the quantitative analysis of photoquadrat benthic images using CoralNet image analysis software, whereby random points are projected on each image and the benthic elements falling directly underneath each point are identified. The images were collected at 18 stratified randomly selected sites in Vatia Bay in 2015 during belt transect surveys of coral demography by the Ecosystem Sciences Division (ESD) of the NOAA Pacific Islands Fisheries Science Center (PIFSC). The benthic cover data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive. The benthic images and coral demography data are described and archived separately.

This data package includes benthic imagery, raw benthic cover, mean benthic cover, and mean macroalgae cover data of Nu'uuli Pala Lagoon and Backreef in American Samoa in 2024, produced from the benthic imagery analysis performed by the Ecosystem Sciences Division (ESD) of the Pacific Island Fisheries Science Center (PIFSC) and funded by the Coral Reef Conservation Program (CRCP). Benthic imagery was collected at 20 randomly-selected sites during coral demographic surveys by the NOAA ESD during the 2024 fly-in mission to American Samoa (MP2502). After processing and sorting site photos, imagery was qualitatively analyzed using the web-based CoralNet image annotation tool. CoralNet projects random points on each image, and the benthic elements falling directly underneath each point are identified by trained scientists. Data from benthic surveys of Nu'uuli Pala Lagoon and Backreef establishes a comprehensive biological baseline for land-based sources of pollution impacts on benthic composition and coral demography. These efforts feed into the higher-level CRCP objectives by establishing an in-situ tracking system to assess the effects of management and mitigation strategies and activities in the target watersheds to reduce land-based sources of pollution impacts on coral reefs. This data was funded by CRCP Project #31454 titled "Develop monitoring capacity of American Samoan jurisdictional partners and observing LBSP impacts on coral reefs".

The State of Hawaii DLNR (Department of Land and Natural Resources) DAR (Division of Aquatic Resources) marine monitoring team conducted surveys for benthic monitoring at 6 locations around Hawaii Island. At the 6 locations, one deep (10 meter) and one shallow (3 meter) site was surveyed through benthic photo quad image collection along 10 fixed transects. These permanent monitoring sites were established as part of the Coral Reef Assessment and Monitoring Program (CRAMP). Sites were paired to represent the shallow and deep habitat at each location. Twenty-five random points were overlaid on each image in CoralNet (coralnet.ucsd.edu) and were annotated by staff members to obtain data for percent cover of benthic taxa.

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. Photoquadrat benthic images were collected in 2015 and 2020 only, via belt transect surveys of coral demography according to protocols established by NOAA National Coral Reef Monitoring Program (NCRMP) in 2015. In 2015, the survey implemented a two-stage stratified random sampling (StRS) design to assess the Vatia benthic 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.

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.