Remote sensing is not just used for measuring the status of reefs. A number of studies are continuing to investigate the scientific and management applications of detailed reef mapping. For example, Roelfsema et al. (2002) have used Landsat TM imagery to investigate the spatial distribution of microalgae on reefs. Andréfouët and Payri (2001) have made large-scale assessments of reef productivity in French Polynesia by using SPOT images to scale-up field measurements of production and calcification in individual lagoonal habitats. Mumby (2001) has developed methods that explicitly link the species composition of individual communities to maps of community distribution. Such methods identify hotspots of beta and habitat diversity and aid spatial decision-making.