Coastal Services Center

---

Coral Reef Mapping

---

Knowing the exact location and distribution of coral reefs is essential to their protection and preservation. Coastal managers in the Pacific Islands are using high-resolution IKONOS imagery to map the location of coral reefs.

The Project: Mapping the Coral Reefs of Hawaii and the U.S. Territories in the Pacific Ocean

In 1998, President Clinton signed Executive Order 13089 to "preserve and protect the biodiversity, health, heritage, and social and economic value of U.S. coral reef ecosystems and the marine environment." A large percentage of the coral reefs addressed by this order are found in Hawaii and the U.S. territories in the Pacific Ocean (Guam, Commonwealth of the Northern Mariana Islands, and American Samoa).

To effectively manage the coral reefs, coastal managers need to know exactly where the corals are located. This information helps managers accomplish the following:

• Determine if coral reefs are adequately protected by existing parks or marine protected areas
• Identify coral reefs at risk from harmful or destructive activities
• Make future comparisons for restoration projects or research studies

Developing Information from IKONOS Imagery

To map submerged features in Hawaii, the scientists need imagery that penetrates the water and captures the seafloor. In addition, they want a high-resolution data set – one that is capable of detecting small features on the seafloor. IKONOS can provide imagery for coral mapping efforts because in clear water it can penetrate up to 30 meters, detect features as small as 4 meters, and be collected at various angles to minimize the sun's reflection and glare off the water.

IKONOS data are multispectral, meaning that the data are captured in four spectral bands (red, blue, green, and near-infrared). Because of the multiple bands, researchers can use more than one method to map corals from the imagery. They can use the imagery for visual interpretation, similar to a traditional aerial photograph, or they can run mathematical models on the spectral data to extract more detailed information.

The Result

NOAA's Center for Coastal Monitoring and Assessment (CCMA) Biogeography Team completed the Hawaii and U.S. Pacific island territories shallow water benthic habitat base maps. Information on these projects can be found at the CCMA Coral Reef Project Web site. This is the first step in effectively managing these federally protected resources. Local resource managers can use these base maps to monitor coral reefs for habitat degradation and to plan restoration projects. Additional uses may include integrating coral maps with pollutant run-off data, information on recreational and commercial fishing, and population growth data to help monitor and protect corals.

Return to top