Several GIS file types illustrating Tongan Coral reef geomorphic structure
Data originally produced by Millennium Coral Reef Mapping Project validated maps provided by the Institute for Marine Remote Sensing, University of South Florida (IMaRS/USF) and Institut de Recherche pour le Développement (IRD, Centre de Nouméa), with support from NASA.
"Comparison of the average hard coral cover between the three five-year periods comprising the last 15 years (2005-09, 2010-14, 2015-19, Tab. 9.3) indicated that there was a high degree of confidence (93%) in the long-term decline, despite the uncertainty in individual yearly estimates. Further, the vast majority (90%) of this decline occurred between 2010-14 and 2015-19, suggesting that the rate of decline in hard coral cover has accelerated during the last five years"
This dataset the extent of coral reefs around Pohnpei. The data layer shown here is a subset of Pohnpei base layer. The original data, so-called Digital Line Graphs (DLSs), were created by U.S. Geological Survey (USGS) for the 1:25,000-scale topographic maps (2001). The shoreline was modified by by University of Guam (UOG) (2017) based on 2016 Worldview-3 satellite imagery from Digital Globe. The dataset was slightly shifted and also updated (mainly around Kolonia and its vicinity).