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NCCOS Project

Benthic Habitat Mapping in American Samoa, Guam, and Commonwealth of the Northern Mariana Islands

This project began in January 2004 and was completed in January 2005

NCCOS produced a georeferenced, digital atlas of benthic habitat maps for the shallow-water (< 30m) coral ecosystem habitats around the U.S. Pacific Territories of American Samoa, Guam, and Commonwealth of the Northern Mariana Islands (CNMI) The maps support a variety of management applications, including informing resource management decisions, ensuring safe navigation, supporting coastal communities, sustaining coastal habitats and mitigating coastal hazards.

Why We Care
Coral reef ecosystems are enormously valuable culturally, ecologically, and economically, but they are declining globally primarily because of human influences. Our ability to better understand, protect, and improve their condition relies on ongoing assessments, and mapping is an important component of those efforts. The maps depict the extent of coral reefs, and are used to monitor reef health over time, help identify which areas need further protection, and which reefs need improved management measures.

What We Did
NCCOS and partners (listed below) completed an assessment in 2005 to map the distribution of coral reefs and other benthic habitats throughout the shallow waters of the U.S. Pacific Territories of Guam, American Samoa, and the Commonwealth of the Northern Marianas Islands. The maps represent the first comprehensive assessment of benthic habitats of the shallow water environments (less than 99 feet water depth) for these Pacific Island Territories.

Many people and organizations made this atlas possible, including: NOAA’s Special Projects Office; NOAA’s Coastal Services Center; NOAA’s National Geodetic Survey; NOAA Pacific Island Fisheries Science Center, Coral Reef Ecosystem Division; NOAA’s Fagatele Bay National Marine Sanctuary; National Park Service, War in the Pacific, National Historic Park; Department of Marine and Wildlife Resources, American Samoa Government; Coral Reef Advisory Group, American Samoa Department of Commerce; University of Guam Marine Laboratory, Division of Aquatic and Wildlife Resources, Guam Department of Agriculture; Bureau of Statistics and Planning, Guam Government; Coastal Resource Management, Commonwealth of the Northern Mariana Islands (CNMI); Division of Environmental Quality, CNMI; Division of Fish and Wildlife, CNMI; Analytical Laboratories of Hawaii; BAE Systems Spectral Solutions LLC; Space Imaging

What We Found
Below is a summary of the benthic areas mapped for each of the detailed structure classes and major cover classes in the American Samoa and Mariana Archipelago study area. The information presented is in absolute areas (km2) and percentage of the total coral reef area mapped.  For American Samoa data, 71.5 km2 were mapped, with ~ 85% being coral reef and hard bottom and ~15% composed of unconsolidated sediment. Of the total area mapped in American Samoa, ~53% is colonized by at least 10% live coral cover. For the Mariana Archipelago, 263.2 km2 were mapped, with ~ 69% being coral reef and hard bottom and ~ 31% composed of unconsolidated sediment. Of the total area mapped in the Mariana Archipelago, about 28% is colonized by at least 10% live coral cover.

Thirty-four distinct benthic habitat types (i.e., four major and fourteen detailed geomorphological structure classes; nine major and five detailed biological cover types) within eleven zones were mapped directly into a geographic information system (GIS) using visual interpretation of orthorectified IKONOS satellite imagery.  Benthic features mapped covered an area of 263 km2 from the shoreline to water depth of about 30 meters. In all, 81 km2 of unconsolidated sediment, 122 km2 of submerged vegetation, and 82 km2 of coral reef and colonized hard bottom were mapped.  Products include an atlas of the benthic habitat maps, posters of the digital maps, satellite imagery, a classification manual, a journal article on the benthic terrain classification scheme for American Samoa, and more – see product section linked below


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