Benthic Surveys in Vatia, American Samoa: comprehensive assessment of coral demography (adult and juvenile corals) from belt transect surveys between 2015-11-02 and 2015-11-12 (NCEI Accession 0165016)

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 nutrient fluxes.

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) according to protocols established by the NOAA National Coral Reef Monitoring Program (NCRMP). In 2015 data were collected at 18 stratified randomly selected sites in Vatia Bay. These data include:

1) an assessment of coral colony density and size-class distribution for the selected monitoring sites;

2) an assessment of coral recruitment at the monitoring sites; and

3) an evaluation of coral colony condition, including mortality, disease, bleaching, and evidence of sediment stress.

These data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive. Additionally, photoquadrat benthic images were collected and analyzed for benthic cover composition (documented and archived separately).

A brief report documenting the 2015 surveys conducted in Vatia and Fagaʻalu in Tutuila, American Samoa by the NOAA Coral Reef Ecosystem Program is in progress: Baseline Assessment of Coral Reef Community Structure and Demographics in Vatia and Fagaʻalu Bays, American Samoa.