A study appearing in the Sept. 6 issue of Nature concludes that airborne multispectral imaging may be a powerful tool for monitoring the health of coral reefs. Researchers on the project from Newcastle upon Tyne University and Sheffield University, both in the UK, the Centre Scientifique de Monaco and the Khaled Bin Sultan Living Oceans Foundation in East Lansing, Mich., reported that aerial estimates of the cover on live coral – an indicator of stress – differed by less than 10 percent from in situ surveys by divers.The researchers employed a 10-band imager with 1-m resolution to study two reefs in the Rangiroa Atoll in French Polynesia, correcting for depth variation with image-derived attenuation coefficients. They noted that it took them an hour to survey the equivalent of 3700 25-m2 plots with the system, while it took three days of diving to survey 10 plots.