American Samoa Benthic Habitat Maps - Prepared by Visual Interpretation from Remote Sensing Imagery

This project is a cooperative effort among the National Ocean Service, National Centers for Coastal Ocean Science, Center for Coastal Monitoring and Assessment; the University of Hawaii; BAE Systems Spectral Solutions; and Analytical Laboratories of Hawaii, LLC. The goal of the work was to map the coral reef habitats of American Samoa, Guam and the Commonwealth of the Northern Mariana Islands by visual interpretation and manual delineation of IKONOS satellite imagery. A two tiered habitat classification system was tested and implemented in this work. It integrates geomorphologic reef structure and biological cover into a single scheme and subsets each into detail. It also includes thirteen zones. Benthic features were mapped that covered an area of 71.5 square kilometers of which 10.56 were unconsolidated sediment and 60.94 were coral reef and hard bottom. Of the coral reef and hard bottom class, 62.8% is colonized by greater than 10% coral cover.

The National Ocean Service is conducting research to digitally map biotic resources and coordinate a long-term monitoring program that can detect and predict change in U.S. coral reefs, and their associated habitats and biological communities. Precise mapping of benthic habitats is essential for developing management strategies that balance the protection of these habitats with their use. Accurate maps of these areas enable resource managers to make informed decisions about the use and protection of the resources.

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Information for this metadata was taken from the individual metadata records for the Pacific Territories Benthic Habitat Mapping Project which can be accessed at http://ccma.nos.noaa.gov/ecosystems/coralreef/us_pac_terr/. For more information refer to the metadata record for the data layer of interest.

The ground validation and accuracy assessment data are delivered as shapefiles and contain information based on the Pacific Territories Benthic Habitat Classification Scheme. Please refer to the individual layer metadata records for more information.

A complete description of the Pacific Territories Benthic Habitat Classification Scheme can be found at http://ccma.nos.noaa.gov/ecosystems/coralreef/us_pac_terr/html/methods.aspx.

These data were prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Although all data have been used by NOAA, no warranty, expressed or implied, is made by NOAA as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by NOAA in the use of these data or related materials.

Contact NOAA for distribution options (see Distributor). All maps of American Samoa prepared during this tenure are incorporated into this metadata summary.;

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Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 1; ESRI ArcCatalog 9.0.0.535

A statistically robust field data set was collected to assess the thematic accuracy of the map products. A random stratified sampling method was implemented to select field sites to conduct this test. Each site was navigated to using a Trimble Geo Explorer 3 GPS data logger, and positional data was acquired. A total of 613 GPS waypoints were occupied and benthic characterizations conducted for the purpose of accuracy assessment.A statistical analysis that generated a Tau statistic was preformed. The Tau statistic for the major classes exceeded 0.85 and for detailed classes exceeded 0.75. Overall thematic accuracy was established as 98.0% and 87.6 for the major structure and cover classes and 84.0% and 75.5% for the detailed classes respectively.

RMS from digitized output was determined using the ESRI RMEer2 extension and shown to be less than 1m when conducted at 1:6000 scale.

NOAA supplied georeferenced imagery to Analytical Laboratories of Hawaii through BAE Systems Spectral Solutions. Delineation of all habitat boundaries was conducted with the image scale at 1:6,000. This ensures that the level of detail produced by the photo interpreter is uniform throughout the project. Also, NOAA has shown from similar mapping efforts in the Caribbean and Florida Keys, that little additional information is gained from having the image at a smaller scale and the labor intensity increased significantly. The minimum mapping unit (MMU) for identifying habitats or features was 1 acre. The software utilized in this project was designed to alert the photo interpreter each time a polygon was drawn smaller than the MMU. When this occurred the photo interpreter has the choice whether to include the polygon in the data set. Only in areas where local coral reef managers expressed interest in specific map classes or in Marine Protected Areas were polygons of smaller then the MMU allowed.

All mapping was conducted from orthorectified IKONOS satellite imagery provided by NOS prior to map production. IKONOS satellite imagery was corrected for atmospheric and water column effects, color balanced, pan sharpened and deglinted. During the digitizing process, image stretches and manipulating image contrast, brightness and color balance were performed in the ArcView Image Analysis Extension to enhance features in the processed imagery. GIS topologic quality was established by executing ArcView extension routines that check for: overlapping polygons, multipart polygons, sliver polygons and void polygons. Additionally checks for adjacent polygons with the same habitat attributes were completed. All errors were identified and corrected. This file is believed to be logically consistent.