National Coral Reef Monitoring Program: Benthic Cover Derived from Analysis of Benthic Images Collected for Climate Stations across American Samoa since 2015

The coral reef benthic community data described here result from the annotation (classification) of benthic images collected during photoquadrat surveys conducted by the NOAA Pacific Islands Fisheries Science Center (PIFSC), Ecosystem Sciences Division (ESD, formerly the Coral Reef Ecosystem Division) as part of NOAA's ongoing National Coral Reef Monitoring Program (NCRMP). The photoquadrat surveys were conducted at coral reef sites according to protocols established by ESD and NCRMP during ESD-led NCRMP missions to American Samoa in 2015, 2018, and 2023.

SCUBA divers conducted benthic photoquadrat surveys at permanent sites established in coral reef habitats by ESD. A select number of these sites were chosen in hard-bottom habitat at ~15-m depths, and a subset of the permanent sites (climate stations) were established at north, south, east, and west points around each of the islands and atolls. The divers estimated and delineated each sites rectangular perimeter by temporarily placing measuring tapes with 1-m markers starting from a permanently installed reference stake on the reef. Along the nearshore 10-m side of the survey site and the downslope 5-m side, the measuring tapes marked every meter of the L-shaped 15-m transect used for photoquadrat documentation. The divers photographed the reef at 1-m intervals on both sides of the 15-m tape, generating 30 photographs per survey site.

The benthic habitat images were quantitatively analyzed using Coral Point Count with Excel extensions (CPCe; Kohler and Gill, 2006) software from 2010-2014 and the web-based annotation tool, CoralNet (Beijbom et al. 2015), from 2015 to present. Ten points were randomly overlaid on each image and human analysts identified the organism or type of substrate beneath, with 300 annotations (points) generated per site. Benthic elements falling under each point were identified to genus/morphology for hard corals, and to genus/functional group for algae, invertebrates, and other taxa following Lozada-Misa et al. (2017). In general, the analysis resulted in three levels of benthic community data, including taxa group Tier 1 (e.g., coral, soft coral, macroalgae, turf algae, etc.), Tier 2 (e.g., Coral = massive hard coral, branching hard coral, foliose hard coral, encrusting hard coral, etc.; Macroalga = upright macroalgae), and Tier 3 (e.g., Coral = Astreopora sp, Favia sp, Pocillopora, etc.; Macroalgae = Caulerpa sp, Dictyosphaeria sp, Padina sp, etc.). If Tier 3 resolution is not possible, the next finest resolution is used.. These benthic data can ultimately be used to produce estimates of relative abundance (percentage of benthic cover), frequency of occurrence, benthic community taxonomic composition, and relative generic richness.

Climate stations are 3-4 sites per island that were selected in a stratified random fashion to be roughly equally spaced around the island, along the 15 m contour, on hard bottom, and at least 1 km away from a river mouth or embayment. Once selected we assess multiple features of the coral reef environment including in-situ temperature (STR), seawater carbonate, net carbonate accretion (CAU), bioerosion (BMU), and cryptobiota diversity (ARMS).

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

The benthic data resulting from the collection and annotation of benthic imagery can ultimately be used to produce estimates of benthic community taxonomic composition, relative abundance (percentage of benthic cover), and frequency of occurrence, which are fundamental to understanding the status and change of coral reef benthic communities.

The NOAA National Coral Reef Monitoring Program (NCRMP) details a long term approach to provide an ecosystem perspective via monitoring climate, fish, benthic, and socioeconomic variables in a consistent and integrated manner. The NCRMP coordinates various NOAA Coral Reef Conservation Program (CRCP) biological, physical, and human dimensions activities into a cohesive NOAA-wide effort. Through the implementation of the NCRMP, NOAA is able to clearly and concisely communicate results of national-scale monitoring to national, state, and territorial policy makers, resource managers, and the public on a periodic basis.

NCRMP is a framework for conducting sustained observations of biological, climate, and socioeconomic indicators at 10 priority coral reefs across the U.S. and its territories. This integrated approach consolidates monitoring of coral reefs under a uniform method in the Pacific, Atlantic, Caribbean, and the Gulf of Mexico for the first time. NCRMP is funded by the CRCP and supported by NOAA Fisheries, NOAA National Centers for Coastal Ocean Science (NCCOS), and many other partners. The PIFSC Ecosystem Sciences Division (ESD) at NOAA Fisheries is leading biological monitoring in the U.S. Pacific Islands Region.

The biological component of NCRMP in the Pacific provides a triennial ecological characterization at a broad spatial scale of general reef condition for reef fishes, corals and benthic habitat (i.e., fish species composition/density/size, benthic cover, and coral density/size/condition). Innovative analysis techniques are then used to develop products that give fellow scientists, managers, decision makers and the public a better understanding of a region's resources and how they are changing over time.

Updated July 2021 to add benthic data generated from images collected in 2018.

Raw survey data includes metadata for each survey (where, when, who); site characteristics (depth, reef zone); unique image name, and individual point observations of benthic elements identified at three levels of benthic community data, including taxa group (Tier 1: hard coral, soft coral, macroalgae, turf algae, etc.), morphology (Tier 2: massive, branching, upright macroalgae, etc.), and genus (Tier 3).

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.

American Samoa including Tutuila, Manu'a (Ofo, Olosega, and Ta'u), Rose Atoll, and Swains.

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NOAA Ecosystem Science Division (ESD) Data Sharing Recommendations, version 9.0 updated August 12, 2015:

ESD welcomes the opportunity to collaborate on research issues contributing to the scientific basis for better management of marine ecosystems. ESD 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 ESD principal investigators.

2) In all presentations, product releases, or publications using data generated by ESD, proper acknowledgement of both ESD 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, ESD requests that you share relevant information on complimentary data collections.

4) Those receiving data are strongly urged to inform the ESD 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 Ecosystem Science Division (ESD), 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 Ecosystem Science Division (ESD) when using the data.

Example:

Ecosystem Science Division (ESD); Pacific Islands Fisheries Science Center (2016). National Coral Reef Monitoring Program: Benthic Percent Cover Derived from Analysis of Benthic Images Collected for Climate Stations across American Samoa in 2015, 2018, and 2023. NOAA's National Center for Environmental Information, https://www.fisheries.noaa.gov/inport/item/25383

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PIFSC Oracle database view: MV_BIA_CNET_ANALYSIS_DATA (CoralNet) / MV_BIA_PERC_COVER_PHOTO_CLI_RW (CPCe)

Data sets derived from image analysis are highly reliable within the stipulated taxonomic context. Each time a production run is performed for a region, a calibration exercise is conducted by all staff that will participate in that round of image analysis classification. Usually 100-150 photos are selected from the photos being processed as part of the production run series, or other region-relevant photo streams. Then, CPCE or CoralNet assigns 10 random points per photo. Each photo analyst is asked to classify the same set of points in each of the photos used as part of the calibration exercise. The goal of the calibration exercise is to assess inter-observer variability. Inter-observer variability rates are available upon request for each production run.

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

Data sets derived from image analysis include 20-30 benthic photographs per survey site from both the climate team surveys. Appropriate site level benthic cover estimates are generated from all site images.

Survey transects were appropriately marked to allow direct, site-level temporal comparisons.

The data set derived from the image analysis is as good as the images themselves; poor images with low contrast, inappropriate white balance, or out of focus may have to be discarded. Therefore, benthic cover estimates for some sites may derive from differing number of points between sites. Although the analysis process is statistically robust to allow for differing n (points) between sites the users should be aware of this limitation.

For REA survey imagery analyzed or collected since 2013, classification is completed to the functional group/genus level (Tier 3).

Only shallow water (0 to 30 meter depth range) hard-bottom habitats are surveyed. The survey sites were randomly selected using a systematic process based on available habitat and bathymetric data. Although efforts are made to include broad spatial coverage of surveys at each island, weather conditions and other environmental constraints may have prevented the team from surveying exposed reef areas.

There are several missions in which the benthic images collected by the program are in the process of or have not yet been analyzed. In some cases, the benthic imagery sets are not planned to be analyzed due to funding and resource constraints. Contact ESD at nmfs.pic.credinfo@noaa.gov for more information.

The same method of image analysis was used at each surveyed site.

Quality control is enforced by means of point-to-point, inter-observer calibration exercises that are conducted before each image analysis production series. Additionally, training modules and standard operating procedures have been developed and documented to ensure improved performance and consistent analysis results produced by multiple analysts.

The image analysis data is captured in two different locations: exported files from CPCe or CoralNet that reside on a file server, which are ingested into a table in the PIFSC Oracle database. Both the file server and PIFSC Oracle database are maintained and regularly backed up by PIFSC ITS.

Benthic photographs were collected during photoquadrat surveys conducted at permanent sites and climate stations in coral reef habitats by the PIFSC Ecosystem Sciences Division. The imagery was later analyzed using Coral Point Count with Excel Extentions (CPCe; 2014 and prior) or CoralNet (starting in 2015) to generate benthic community data.