A synthesis of benthic percent cover data in the Mariana Islands Archipelago covering a period of 22 years (2000-2022) and summarized at three spatial scales (archipelago-, isla...

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.

The National Coral Reef Monitoring Program (NCRMP) was explicitly designed to summarize coral reef site-level data at the regional and island scales. While the results are geographically comprehensive, this sampling design limits the utility of the NCRMP dataset to inform local resource management decisions at sub-island scales. Accordingly, managers typically rely on smaller-scale efforts that trade spatial comprehensiveness for finer spatiotemporal resolution. To reconcile managers' scale of interest and better leverage NCRMP data, we present an effort to integrate NCRMP with local coral reef Monitoring data to assess the temporal variation in fish and benthic communities over the last two decades. We identified common community metrics from all monitoring programs, compared these metrics between populated and remote islands, and analyzed their trends at the island- and downscaled sector-scales (sub-island spatial units that are homogeneous in benthic cover).

Our integrated benthic data set (from NCRMP and our jurisdictional monitoring programs) resulted in 2,298 observations from 1,800 unique locations across the Marianas and spanned over two decades (2000-2022). From these data, we observed a general decline in hard coral cover which was accompanied by a substantial increase in turf algae across the archipelago. These trends were present at smaller spatial scales (islands and sectors). Specifically, coral cover significantly declined at three of the four populated islands and in 50% of the sectors. When gauging resilience, our results revealed evidence of reef resistance for some sectors, which represent potential good candidates for resilience-based spatial management. Overall, this project combined different data streams, covered a wide spatiotemporal scale, and employed a spatial downscaling approach to unveil patterns of resilience at management-relevant scales.

Gajdzik L, Ingeman K, Kindinger TL, Oliver T. 2023. Spatiotemporal trends in benthic and reef fish communities in the Mariana Archipelago. U.S. Dept. of Commerce, NOAA Technical Memorandum NMFS-PIFSC-152, 45p. 45. doi:10.25923/7efh-qt23

University of Guam Marine Laboratory (2019). Guam Long-term Coral Reef Monitoring Program Benthic Images since 2010. NOAA's National Center for Environmental Information, https://www.fisheries.noaa.gov/inport/item/47788.

Pacific Islands Fisheries Science Center, 2024: National Coral Reef Monitoring Program: Benthic Cover Derived from Analysis of Benthic Images Collected during Stratified Random Surveys (StRS) across the Mariana Archipelago since 2014, https://www.fisheries.noaa.gov/inport/item/36156.

Pacific Islands Fisheries Science Center, 2024: National Coral Reef Monitoring Program: Benthic Images Collected from Stratified Random Sites (StRS) across the Mariana Archipelago since 2014, https://www.fisheries.noaa.gov/inport/item/36153.

Pacific Islands Fisheries Science Center, 2024: Pacific Reef Monitoring and Assessment Program: Line-Point-Intercept (LPI) Surveys for Benthic Cover at Coral Reef Sites across the Pacific Ocean from 2005 to 2012, https://www.fisheries.noaa.gov/inport/item/25261.

Pacific Islands Fisheries Science Center, 2024: National Coral Reef Monitoring Program: Benthic Cover from Annotated Benthic Images Collected During Photoquadrat Surveys at Climate Stations across the Mariana Archipelago since 2014, https://www.fisheries.noaa.gov/inport/item/36147.

Perez, D.I., Camacho, R., Hasegawa, K., Iguel, J., Suel, J., David, P. (2021). CNMI State of the Reef Report 2020-2021. Division of Coastal Resources Management, Bureau of Environmental and Coastal Quality, Commonwealth of the Northern Mariana Islands.

Dataset includes metadata for each survey site (date, archipelago, island, and site name); site characteristics (reef zone - only forereef); and benthic cover estimates where the benthos was characterized in four main groups: (i) coral (strictly hard scleractinian live corals), (ii) algae (excluding turf), (iii) turf algae,(iv) crustose coralline algae (CCA), (v) calcified (i.e., corals, CCA, and other calcifiers such as Halimeda algae) and (vi) non-calcified (non-calcifying algae, sponges, and other non-calcified living).

Data dictionary defines columns in the spatiotemporal benthic cover dataset.

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.

Mariana Archipelago (Guam and the Northern Mariana Islands, including Agrihan, Aguijan, Alamagan, Asuncion, Guguan, Maug, Pagan, Rota, Saipan, Sarigan, and Tinian).

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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 Ocean Acidification Program (OAP). 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 Fisheries, Ecosystem Science Division (ESD) when using the data.

Example:

Ecosystem Science Division; Pacific Islands Fisheries Science Center, 2024: A synthesis of benthic percent cover data in the Mariana Islands Archipelago from 2000 to 2022 summarized at three spatial scales (archipelago-, island-, and sub-island-scales), https://www.fisheries.noaa.gov/inport/item/72575.

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Benthic cover estimates derived from four datasets are available in a csv file and means were computed in R.

Only good images of the benthos (for the photoquadrat methods) were kept and those with poor resolution, poor lighting, extraneous objects (fins, etc), or blur were excluded from analysis. For the line-intercept points, the benthic cover parameter observations were made by trained divers.

Image data include ~30 benthic photographs per survey site. The diver teams conduct the photoquadrat surveys along one 30-m transect. Appropriate site level image grouping should include all 30 images.

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

Only photoquadrats and line-point intercept methods of data collection were used at each surveyed site and coarse benthic cover estimates were computed from those data.

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.

NOAA IRC and NOAA Fisheries ITS resources and assets.

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).