Benthic habitat maps of the nearshore marine environment of Majuro, Republic of the Marshall Islands were created by visual interpretation of remotely sensed imagery. The objective of this effort, conducted by NOAA's Center for Coastal Monitoring and Assessment - Biogeography Branch was to provide spatially-explicit information on the reef zones and habitat types of Majuro's coral reef ecosystem.
This product provides a fine-scale assessment of the status, abundance, and distribution of marine habitats of Majuro. The work provides local scientisits and managers with increased technical capacity for ocean exploration, management, and stewardship. Direct applications to management include evaluation of management efficacy, a spatial framework for improved monitoring and sampling design, improved assessment of human-use impacts, and marine spatial planning to support consideration of marine protected area boundary alternatives.
ground condition
Not for navigation.
1305 East West Highway
A comprehensive assessment to evaluate the thematic accuracy of the Majuro benthic habitat map has not yet been conducted. The approach used at Majuro is expected to yeild accuracies for detailed structure that are similar to those calculated for other recent NOAA benthic habitat maps such as those in Palmyra Atoll (84%), St.John USVI (85.7%) in the Florida Keys (86.2%), Palau (90.0%), and the Main Hawaiian Islands (90.0%).
Benthic habitats were visually interpreted from Digital Globe’s Quickbird II (QB2) commercial satellite imagery collected between 2004 and 2006. The satellite collects a four-channel multispectral image (blue, green, red, and near infra-red colors) at 2.44 m spatial resolution as well as a panchromatic image (black and white) at 0.61 m resolution. NOAA fused these two images to create “pansharpened” scenes for mapping that have the high spatial resolution of the panchromatic image and the colors of the multispectral image. During the digitizing process, image stretches and manipulating image contrast, brightness and color balance were performed in ArcGIS to enhance features in the processed imagery. GIS topologic quality was established by executing ArcGIS extension routines that check for: overlapping polygons, multipart polygons, sliver polygons and void polygons. 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.
Delineation of all habitat boundaries was conducted with the image scale at 1:4,000. This ensured that the level of detail produced by the photo interpreter was uniform throughout the project. The minimum mapping unit (MMU) for identifying habitats or features was 1,000 square meters. The software utilized in this project was designed to alert the photo interpreter each time a polygon was drawn smaller than the a MMU; at which point the polygon was then aggregated with the most logical adjacent polygon.
NOAA calculations with 21 known ground control locations resulted in RMSE accuracy of 1.619 m. It is believed that polygon horizontal accuracies are inherited from the source imagery.
This section of the report describes the habitat classification scheme used to classifiy habitat features. The Majuro habitat classification scheme defines benthic communities on the basis of four primary coral reef ecosystem attributes: 1) broad geographic zone, 2) geomorphological structure type, and 3) percent hardbottom.
This ArcGIS extension was used to digitize and attribute benthic zones, structure and biological cover of this map.
Used to identify and digitize benthic habitats of Majuro.
1) Imagery Acquisition - The first step in map creation was the acquisition and processing of a comprehensive dataset of remotely sensed imagery. All imagery was geo-positioned to ensure acceptable spatial accuracy in the mapping product.
NOAA/NOS/NCCOS/CCMA, N/SCI1
1305 East-West Hwy, 9th floor
2) Habitat Boundary Delineation - A first draft benthic habitat map was generated by delineating all features that could be identified by visual inspection of the remotely sensed imagery. During the creation of this first draft, the interpreter placed discrete points on the map that were representative of all image signatures and/or difficult to identify and that warranted further field investigation. These sites were labeled as "ground validation" positions.
3) Ground Validation - NOAA field scientists explored the ground validation locations with a suite of assessment techniques depending on the conditions at each site. A combination of underwater video, free diving, snorkeling and surface observations were used to survey the ecological characteristics at each location. This information was analyzed and the initial maps were edited to generate a second draft map.
4) Final Products Creation - A final benthic habitat map for Majuro was generated by correcting inaccuracies elucidated by quality control procedures. Additionally, all associated datasets, including GIS files, satellite imagery and metadata were packaged for web delivery.
Internal feature number.
ESRI
Feature geometry.
A distinct identifier used to define each unique combination of habitat characteristics
NOAA
Calculated feature area
Geographic zone
Major Geomorphological Structure
Detailed Geomorphological Structure
Percent hardbottom of the polygon
Specific details of the attributes and values therein can be found in Kendall et al. 2012. Benthic Habitats of Majuro, Republic of the Marshall Islands. NOAA Biogeography Branch Report.
Kendall et al. 2012. Benthic Habitats of Majuro, Republic of the Marshall Islands. NOAA Biogeography Branch Report.
The National Oceanic and Atmospheric Administration (NOAA) National Centers for Coastal Ocean Science (NCCOS) is publishing this data on their website. NCCOS Biogeography Branch does not guarantee the accuracy of the geographic features or attributes. Please see the written report and metadata records for each data set for complete information on the source, limitations, and proper use.
Contact NOAA for distribution options (see Distributor).
