We conducted benthic habitat mapping of shallow-water coral reef areas off Puerto Rico and the U.S. Virgin Islands to inventory the coral reefs and related bottom types. Before this project, a comprehensive inventory of the shallow-water reefs in these areas did not exist. Such an inventory is needed for successful coral reef ecosystem management. This represents the first U.S. coral reef area to be mapped under the purview of the U.S. Coral Reef Task Force.

Why We Care
Coral reef ecosystems are enormously valuable culturally, ecologically, and economically, but they are declining 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. Maps provide not only past and present data on the condition of our coral reefs, they also reveal the effectiveness of coral reef conservation activities over time, which areas need further protection, and which need alternate management measures.

What We Did
We acquired aerial photographs of the nearshore waters of Puerto Rico and the U.S. Virgin Islands in 1999. These images, along with field sampling for validation, were used to create geographic information system (GIS) maps of the study area’s coral reefs, seagrass beds, mangrove forests, and other important marine habitats. Mapped areas encompass the insular shelf between the shoreline and shelf edge, except where turbidity prevented visualization of the bottom. Products include GIS maps of benthic habitats, aerial photographs, an online benthic habitat atlas, along with a detailed methods manual for creating the benthic habitat maps.

Our partners included:

• Government of the Virgin Islands Department of Planning and Natural Resources (VIDPNR)
• Commonwealth of Puerto Rico, Department of Natural and Environmental Resources
• Caribbean Fisheries Management Council
• National Park Service
• NOAA, National Geophysical Data Center
• NOAA, Coastal Services Center
• NOAA, National Geodetic Survey
• St. Croix Environmental Association

What We Found and Benefits of our Work
We mapped 21 distinct benthic habitat types within eight zones and added these data to a GIS using visual interpretation of orthorectified aerial photographs. We mapped benthic features that covered an area of 1600 km² in Puerto Rico and 490 m² in the U.S. Virgin Islands. In Puerto Rico, we mapped 721 km² of submerged vegetation, 756 km² of coral reef and colonized hardbottom, 49 m² of unconsolidated sediment, and 73 km² of mangroves. In the U.S. Virgin Islands, we mapped 300 km² of coral reef and hard bottom, 161 km² of submerged vegetation, 24 km² of unconsolidated sediment, and 2 km² of mangroves. Since 2002, these maps have been used for a wide range of applications, including: coral reef monitoring, marine protected area design, fisheries assessments, and student projects.

Next Steps
We continue to map and document the shallow-water coral reef ecosystems and benthic habitats in this area using new remote sensing imagery and higher resolution data.