Benthic Habitat Maps for Rose Atoll Marine National Monument in American Samoa from 2004 to 2010

Benthic habitat maps for Rose Atoll, American Samoa were derived from high resolution, multispectral satellite imagery for 2004, 2006, and 2010. The benthic habitat maps for 2004 were previously generated by NOAA's NCCOS's BioGeography Branch before this project, and they were gathered from NOAA's 2005 publication (NCCOS, 2005). The benthic habitat maps for 2006 and 2010 were generated in this project. Bathymetry (water depth) from 0 to 30 meters was derived from satellite imagery for 2006 and 2010 and validated with multibeam and singlebeam depth data, respectively. Eight geomorphological features of the seafloor (Mean Depth, Standard Deviation of Depth, Slope, Slope of Slope, Rugosity, Curvature, Plan Curvature, and Profile Curvature) were derived from the bathymetry for 2006 and 2010. The geomorphological features were used to perform a Principal Component Analysis (PCA), and the first three Principal Components were used in combination with classified benthic imagery (underwater images of the seafloor) to classify the underwater habitat of the inner lagoon and sloping reef areas of Rose Atoll.

The final benthic habitat maps consist of two maps for each of the three years. The first map shows the four dominant cover types that make up the shallow water benthic habitat on Rose Atoll, which are coral, coralline algae, macroalgae, and turf algae. The area in square kilometers of each cover types is provided. The purpose of the first map is to show the most abundant biological cover types in the benthic habitat. The second map show the percentages of the four dominant cover types, which are divided into three bins: 10%-<50% coverage, 50%-<90% coverage, and 90%-100% coverage. The area in square kilometers of each of the cover types is also provided. The purpose of the second map is to examine the smaller changes in the benthic habitat over the three years.

The benthic habitat maps were prepared by the Coral Reef Ecosystem Program (CREP) and funded by the Coral Reef Conservation Program (CRCP), in order to determine the feasibility of an automated image analysis program known as CoralNet. These maps were also used in a graduate research project, in order to examine any spatial and temporal changes in the shallow water benthic habitat of Rose Atoll in the years where sufficient spatial data were available. Therefore, the spatial and temporal changes in the shallow water benthic habitat were examined for the years 2004, 2006, and 2010.

NCCOS, N. (2005). Atlas of the shallow water benthic habitats of American Samoa, Guam, and the Commonwealth of the Northern Marianas Islands. NOAA Tech. Memo. NOS NCCOS. 8.

The Dominant Cover Type maps show four dominant cover types (Coral, Coralline Algae, Macroalgae, and Turf). The Percentages of Biological Cover Type maps show three percentages for each cover type (10-<50%, 50-<90%, 90-100%).

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.

Rose Atoll, 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 Pacific Islands Benthic Habitat Mapping Center (PIBHMC) website at http://www.soest.hawaii.edu/pibhmc/cms/data-by-location/american-samoa/rose-atoll/rose-atoll-habitat/.

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These data are not to be used for navigation purposes.

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

Suggested citation:

Roberson, Liana; Coral Reef Ecosystem Program; Pacific Islands Fisheries Science Center (2017). Benthic Habitat Maps for Rose Atoll Marine National Monument in American Samoa from 2004 to 2010. Pacific Islands Benthic Habitat Mapping Center, https://www.fisheries.noaa.gov/inport/item/46886.

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Coral Point Count with Excel Extensions (CPCe) was used to classify benthic images (underwater images) of the seafloor. Environment for Visualizing Images (ENVI) was used to analyze the satellite imagery of Rose Atoll. ArcGIS for Desktop's Spatial Analyst Tools, 3D Analyst Tools, Benthic Terrain Modeler (BTM) Tools, Principle Component Analysis (PCA) Tool, and the Maximum Likelihood Classification (MLC) tool were used to derive bathymetry, the eight geomorphological features of the seafloor, and classify the underwater habitat for the three years.

The thematic maps showing the Dominant Cover Types and Percentages of Dominant Cover Types accurately depict the seafloor habitat of the inner lagoon and outer sloping areas of Rose Atoll for the three years, 2004, 2006, and 2010. The area where the benthic habitat is classified is between 0 to 30 meters, and high-resolution, multispectral satellite imagery was used to fill in any data gaps in the gridded bathymetry derived from multibeam and single beam sonars.

Accuracy of multibeam sonar acquired in 2006, which was used to create the 2006 benthic habitat maps:

POSITIONAL ACCURACY:

Horizontal Positioning System: GPS C/A

Horizontal Position Accuracy: 25 meters

VERTICAL POSITIONAL ACCURACY:

Range Resolution of Sonar: Varies with Depth

Raw Resolution of Sonar: Varies with Depth

Vertical Accuracy of Gridded Sonar Product: ~ 1% of water depth

Vertical Accuracy of Derived Bathymetry Product: 5 meter range

Accuracy of single beam sonar acquired in 2012 and 2015, which was used to create the 2010 benthic habitat maps:

POSITIONAL ACCURACY:

Horizontal Position Accuracy: 6.42 m ± 0.02 (2012), 3.01 m ± 0 (2015)

VERTICAL POSITIONAL ACCURACY:

Vertical Accuracy of Gridded Sonar Product: 0.02 m ± 0.01 (2012), 0.65 m ± 0.02 (2015)

Benthic habitat classifications were determined for the shallow (0 to 30 meters) area of Rose Atoll for all areas visible in the satellite imagery that were used to derive estimated depths. Some data gaps exist in the bathymetry coverage due to features in the satellite imagery that prevent data derivation such as clouds, waves, etc.

Estimated depths generated by the Coral Reef Ecosystem Program (CREP) were processed in the same manner using the same methods for the years 2006 and 2010. The bathymetry data used were processed in the same manner by the Pacific Islands Benthic Habitat Mapping Center (PIBHMC). Seafloor imagery was collected by two different NOAA offices using different methods; however, all imagery included in this project for the purposes of ground-truthing was classified by CREP using the same classification scheme by experienced image analysts that are tested and calibrated.

The satellite-derived water depths were validated against available multibeam and single beam bathymetry data for the years 2006 and 2010. Corrections for tide variation and vessel attitude are applied to the multibeam and single beam data, and a CTD (Conductivity, Temperature, and Depth instrument) cast is performed regularly during data collection to correct for variance within the water column. Multibeam and single beam data are tested for internal consistency; however, no effort is made to compare these data to external references or to other published data.

University of Hawaii School of Ocean and Earth Science and Technology, NOAA IRC and NOAA Fisheries ITS resources and assets.

To create the benthic habitat maps showing Dominant Cover Types and Percentages of Dominant Cover Types of the shallow water benthic habitat of Rose Atoll for 2006 and 2010, the Maximum Likelihood Supervised Classification (MLC) tool in ArcGIS for Desktop was used to classify the three bands from the Principle Component Analysis (PCA) performed on the eight derived geomorphological features of the seafloor.