Benthic Surveys in Vatia, American Samoa: comprehensive assessment of coral demography (adult and juvenile corals) from belt transect surveys in 2015 and 2020

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.

These data were generated from benthic surveys undertaken in Vatia Bay to establish a comprehensive baseline, status, and trends for benthic composition and coral demographics, and are part of a broader NOAA Coral Reef Conservation Program (CRCP) funded project led by NCCOS and ESD to assess eutrophication impacts on coral ecosystem health in the bay. 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.

Vargas-Angel B, Schumacher BD. 2018. Baseline surveys for coral reef community structure and demographics in Vatia Bay and Faga'alu Bay, American Samoa. Pacific Islands Fisheries Science Center, PIFSC Special Publication, SP-18-002, 38 p. https://doi.org/10.7289/V5/SP-PIFSC-18-002.

and

Vargas-Ángel B, Huntington B. 2020. Status and Trends Assessment of Benthic Coral Reef Communities in Vatia Bay, American Samoa, 2015–2020. Pacific Islands Fisheries Science Center, PIFSC Data Report, DR-20-020, 34p. https://doi.org/10.25923/r7dd-wg50, https://repository.library.noaa.gov/view/noaa/27437

Monthly water quality sampling for nitrate/nitrite, ammonium, urea, total nitrogen, orthophosphorus, and total phosphorus data are also collected as part of this project to quantify the nutrient dynamics of the Bay. These additional data are described separately by the NOAA National Centers for Coastal Ocean Science (NCCOS); see citation below.

Whitall, D, M Curtis, A Mason, B Vargas-Angel. 2019. Excess Nutrients in Vatia Bay, American Samoa: Spatiotemporal Variability, Source Identification and Impact on Coral Reef Ecosystems. NOAA Technical Memorandum NOS NCCOS 266. Silver Spring. 69 pages. doi:10.25923/j8cp-x570

Raw data include individual colony records with the corresponding physical data which reflect the description of the site.

An individual colony record for adult corals includes colony species/genus identification, morphology, maximum diameter (centimeter), percent old dead, percent recent dead, cause of recent dead general category, cause of recent dead specific category, condition, extent and severity. https://www.fisheries.noaa.gov/inport/item/30772

Juvenile coral colony records include colony species/genus identification, morphology, maximum diameter (centimeter). https://www.fisheries.noaa.gov/inport/item/30773

The physical record for juvenile and adult corals includes the following: region, island, site, date (day, month, year), latitude (decimal degrees), longitude (decimal degrees), transect, segment, segment length, segment width, minimum depth (feet), and maximum depth.

While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

Vatia Bay, Tutuila, American Samoa

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NOAA Coral Reef Ecosystem Program (CREP) Data Sharing Recommendations, version 9.0 updated August 12, 2015:

CREP welcomes the opportunity to collaborate on research issues contributing to the scientific basis for better management of marine ecosystems. CREP has a very diverse set of field activities that generates large volumes of data using an array of data collection protocols.

The following recommendations are for your consideration as you use this data:

1) Data analyses should take all field exigencies into account. The most effective way to do this would be active collaboration with CREP principal investigators.

2) In all presentations, product releases, or publications using data generated by CREP, proper acknowledgement of both CREP and the individuals responsible for data collection is expected. Citing the DOI (if available) is preferred, a non-DOI example is listed below.

3) If you collect or generate data for the same study areas, CREP requests that you share relevant information on complimentary data collections.

4) Those receiving data are strongly urged to inform the CREP Data Management Team of any errors and discrepancies that are discovered during the course of using these data. They are further urged to bring to the attention of the Team all problems and difficulties encountered in using these data. This information is necessary in order to improve the collections and to facilitate more efficient and economical data processing and retrieval. The users are asked to supply copies of any missing data that may be located, and to provide information as to significant subsets and special aggregations of data that are developed in using the material provided.

Example citation:

"This publication makes use of data products provided by the Coral Reef Ecosystem Program (CREP), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), with funding support from the NOAA Coral Reef Conservation Program (CRCP). The analysis and interpretations presented here are solely that of the current authors.”

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

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Please cite NOAA Coral Reef Ecosystem Program (CREP) when using the data.

Example

Cite as: Vargas-Angel, Bernardo; Coral Reef Ecosystem Program; Pacific Islands Fisheries Science Center (2017). Benthic Surveys in Vatia, American Samoa since 2015: comprehensive assessment of coral demography (adult and juvenile corals) from belt transect surveys in 2015. NOAA National Centers for Environmental Information. https://www.fisheries.noaa.gov/inport/item/30771

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PIFSC Oracle database views: v0_coral_obs_e and v0_coral_obs_f (date and location selection criteria required to subset the dataset)

Observations were made by experienced benthic survey personnel who have been trained, undergone a series of calibration surveys and coral taxon identification testing, and have met a set of minimum standards for colony assessment and taxon identification in each region. The accuracy of species and genus level identification was high. The lowest taxonomic level of coral identification was genus except for a select number of species that were consistently identified to species by all divers conducting the surveys.

Handheld GPS units were used to locate sites and mark site locations.

The taxon code AAAA is included where the segment was surveyed and no individual colonies were found in both the juvenile and adult colony records. These are true zeros. The value -9 is a placeholder or missing value for the fields: colony length, colony width (juveniles), extent, and severity. The value -1 is included where a coral colony is a fragment.

While colony lengths are derived from physical measurements, recent and old mortality are visual estimates; surveyors calibrate to reduce inter-observer bias

Site GPS location and depth are appropriately collected to allow spatiotemporal comparisons.

Complete. All planned demographic data were collected.

Only forereef, hard bottom habitats were surveyed.

Survey methods were consistent across all sites.

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.

NOAA IRC and NOAA Fisheries ITS resources and assets.

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).