Data Management Plan

The benthic percent cover data described in this record is a result of a synthesizing effort led by the Ecosystem Sciences Division (ESD) to integrate benthic cover data collected during the National Coral Reef Monitoring Program (NCRMP) surveys in the Mariana Islands Archipelago with surveys carried out by jurisdictional partners in Guam and the Commonwealth of the Northern Mariana Islands (CNMI). This project covers a period of over 20 years (2000-2022) and was funded by the CRCP Project #31364, titled "Synthesizing data to assess temporal trends in benthic and reef fish communities across the Mariana archipelago".

Benthic percent cover was estimated for six categories (i.e., calcified, non-calcified, algae, turf, crustose coralline algae, and coral) and produced at three spatial scales: across the archipelago (populated islands versus remote islands), at each populated island (Guam, Rota, Tinian, and Saipan) and some remote islands, and for each downscaled sectors (10 sectors in Guam, four in Rota, four in Tinian, and 9 in Saipan). These estimates were primarily generated from benthic substrate photographs and using the line-point intercept methodology. Benthic substrate photographs are commonly taken along a 30-m transect at every meter at each site and are then analyzed using the web-based annotation tool. The line-point-intercept methodology consists of consecutively placing 25-m line transects (with a usually 5-m inter-transect distance) to determine the benthic composition at predetermined intervals along the transect line.

Extent of surveys in the Marianas

Lineage Statement:
Estimates of benthic cover were primarily generated from benthic substrate photographs (hereafter referred to as “photoquadrats”) and using the line-point intercept methodology. Photoquadrats are commonly taken along a 30-m transect at every meter at each site. The benthic photoquadrat imagery is then analyzed using the web-based annotation tool such as CoralNet; generally 10 random points are selected per photo. The line-point-intercept methodology consists of consecutively placing 25-m line transects (with a usually 5-m inter-transect distance) to determine the benthic composition at pre-determined intervals along the transect line. All living benthic elements (e.g., coral, algae, and other sessile invertebrates) are identified to the lowest taxonomic level possible, often substituting functional group categories for turf algae and crustose coralline algae. The resulting list of datasets was then summarized on relatively coarse metrics of benthic functional groups (i.e., benthic % cover) that allowed us to retain the maximum number of data sets. Where raw data included sub-samples within sites (e.g., multiple, non-independent transects at a single study site), site-level means were calculated to ensure comparability among data sets. Individual data sets were then compiled into a common format with percent cover of (i) hard coral (strictly scleractinian live corals), (ii) macroalgae (excluding turf), (iii) turf, and (iv) crustose coralline algae (CCA). In addition to these functional groupings, we also investigated trajectories and trends over time between calcified cover (i.e., corals, CCA, and other calcifiers such as Halimeda algae) and non-calcified cover (non-calcifying algae, sponges, and other non-calcified living substrates, excluding pavement, rock, sand, and other non-living substrates).

These data underwent quality control procedures during the synthesizing process. However, given the size of the data set, there remains some possibility of typographical or other errors.

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

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