Benthic Cover Derived from Analysis of Benthic Images Collected in the Hawaiian Archipelago During the 2019 Bleaching Event

The data described here result from benthic photo-quadrat surveys conducted along transects at stratified random sites (StRS), as well as climate stations and permanent sites, surveyed across the Hawaiian Archipelago during the 2019 bleaching event. Benthic habitat imagery was quantitatively analyzed using the web-based annotation tool CoralNet (Beijbom et al. 2016) with the addition of codes for bleaching of hard coral. In general, images are analyzed to produce three functional group levels of benthic cover: Tier 1 (e.g., hard coral, soft coral, macroalgae, turf algae, etc.), Tier 2 (e.g., Hard Coral = massive, branching, foliose, encrusting, etc.; Macroalgae = upright macroalgae, encrusting macroalgae, bluegreen macroalgae, and Halimeda, etc.), and Tier 3 (e.g., Hard Coral = Astreopora sp, Favia sp, Pocillopora, etc.; Macroalgae = Caulerpa sp, Dictyosphaeria sp, Padina sp, etc.). For each category of hard coral, a bleached and non-bleached option existed during analysis to facilitate the collection of coral bleaching percent cover data.

In the Main Hawaiian Islands (MHI) and some sites in the Northwestern Hawaiian Islands (NWHI), a StRS design was employed to select random sites. 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 island, reef zone, and depth in all regions, as well as habitat structure type in the Main Hawaiian Islands. Sampling effort was allocated based on strata area and sites were randomly located within strata. Sites were surveyed using photo-quadrats along transects to collect benthic imagery to ultimately produce estimates of relative abundance (percent cover), frequency of occurrence, benthic community taxonomic composition and relative generic richness.

The StRS design effectively reduces estimate variance through stratification using environmental covariates and by sampling more sites rather than sampling more transects at a site. Therefore, site-level estimates and site to site comparisons should be used with caution.

Surveys conducted in the Main Hawaiian Islands were conducted during shore-based missions and were all StRS, whereas surveys in the Northwestern Hawaiian Islands were performed opportunistically during the regularly scheduled NOAA National Coral Reef Monitoring Program (NCRMP) mission and encompassed StRS as well as fixed sites, which include climate stations and permanent sites

The data from the benthic cover surveys can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

Working with the Hawaii Coral Bleaching Collaborative (HCBC), NOAA ESD planned and executed a field survey response in 2019 that applied a structured, hypothesis-driven approach to document the extent of coral bleaching in the Hawaiian Archipelago, and laid the groundwork for tracking coral response and recovery through time.

Raw survey data includes metadata for each survey (where, when, who, area); site characteristics (depth, reef type, habitat); unique image name and individual point observations identified at three functional group levels of benthic cover: Tier 1 (e.g., hard coral, soft coral, macroalgae, turf algae, etc.), Tier 2 (e.g., Hard Coral = massive, branching, foliose, encrusting, etc.; Macroalgae = upright macroalgae, encrusting macroalgae, bluegreen macroalgae, and Halimeda, etc.), and Tier 3 (e.g., Hard Coral = Astreopora sp, Favia sp, Pocillopora, etc.; Macroalgae = Caulerpa sp, Dictyosphaeria sp, Padina sp, etc.). For each category of hard coral, a bleached and non-bleached option existed during analysis to facilitate the collection of coral bleaching percent cover data. The labelset ("CNET_LABELS_BLEACHING") used to annotate in CoralNet can be found under 'Distribution Info,'

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.

Hawaiian Archipelago including the main and Northwestern Hawaiian Islands.

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NOAA Ecosystem Sciences 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 Coral Reef Ecosystem Program (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 Sciences Division (ESD) when using the data.

Example:

Ecosystem Sciences Division; Pacific Islands Fisheries Science Center (2022). Benthic Cover Derived from Analysis of Benthic Images Collected in the Hawaiian Archipelago During the 2019 Bleaching Event. NOAA's National Center for Environmental Information, https://www.fisheries.noaa.gov/inport/item/59195

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PIFSC Oracle database view: MV_BIA_CNET_ANALYSIS_DATA (CoralNet)

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, 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 random sites and mark site locations.

Image data include 30 benthic photographs per survey site. Appropriate site level image grouping should include all 30 images.

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, percent cover estimates for some sites may derive from differing numbers 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.

Imagery annotations are completed to the functional group/genus level (Tier 3).

Only shallow water (0 to 30 meter depth range) hard-bottom habitats are surveyed. The StRS 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.

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. Training modules and standard operating procedures have also been developed and documented to ensure improved performance and consistent imagery analysis results produced by multiple analysts.

NOAA IRC and NOAA Fisheries ITS resources and assets.

The stratified random sampling (StRS) design and benthic photoquadrat survey methodology, employed by the NOAA Coral Reef Ecosystem Program (CREP) since 2013. Benthic imagery is collected at stratified random sites as well as at fixed sites which can be classified as climate stations or permanent sites. The imagery is analyzed using CoralNet to derive benthic cover values. A bleaching label set was produced to perform a bleaching analysis of benthic cover data.