Description

Global map of shallow, tropical coral reefs, gridded at 500-m resolution for use in the Reefs at Risk Revisited project.

The coral reef location data were compiled from multiple sources by UNEP-WCMC, the WorldFish Center, and WRI. To standardize these data for the purposes of the Reefs at Risk Revisited project, data were converted to raster format (ESRI grid) at 500-m resolution. The original sources for the data include: 1. Institute for Marine Remote Sensing, University of South Florida (IMaRS/USF) and Institut de Recherche pour le Développement (IRD/UR). “Millennium Coral Reef Mapping Project,” 2009 (30 m Landsat data classified and converted to shapefile). 2. UNEP-WCMC. “Coral Reef Map,” 2002. 3. Additional data have been acquired or digitized from a variety of sources. Scales typically range from 1:60,000 to 1:1,000,000. See the metadata for additional details.

The coral reef location data were compiled from multiple sources by UNEP-WCMC, the WorldFish Center, and WRI. To standardize these data for the purposes of the Reefs at Risk Revisited project, data were converted to raster format (ESRI grid) at 500-m resolution. The original sources for the data include: - Institute for Marine Remote Sensing, University of South Florida (IMaRS/USF) and Institut de Recherche pour le Développement (IRD). Millennium Coral Reef Mapping Project, 2009 (30 m Landsat data classified and converted to shapefile). - UNEP-WCMC. Coral Reef Map, 2002. - Additional data have been acquired or digitized from a variety of sources. Scales typically range from 1:60,000 to 1:1,000,000. Sources include: the United Kingdom Hydrographic Office, Petroconsultants (CES) Ltd, NOAA, UNEP/IUCN, United States Department of the Interior (USDI) Geological Survey, Department of Lands and Survey (DLS), Directorate of Overseas Surveys (DOS), Great Barrier Reef Marine Park Authority, Wildlife Conservation Society-Fiji, Florida Department of Environmental Protection, Instituto Geográfico Nacional (IGN), Reefs at Risk in Southeast Asia (World Resources Institute), National Mapping and Resources Information Authority (NAMRIA), Digital Chart of the World, Google Earth, REBIOMA, World Wildlife Fund-Salary Bay, Shell, and University of the Philippines Marine Sciences Institute. - Due to variation in the scale, precision, and source of coral reef input data (see above), the geo-processing of the global map of coral reefs involved converting polyline and polygon reef layers into a 500-m resolution raster grid. The gridding process included the following steps: 1. Coral reefs that were mapped as polylines were buffered to an extent of 300 m and then merged with the polygon map of coral reefs. 2. The polygon map of coral reefs was converted to grid such that if a reef polygon covered at least 8% of a 500-m grid cell, then the grid cell was considered a reef grid cell. This gridding methodology was performed to avoid either over- or underestimating coral reef area due to the differences in the input data.