The coral in Australia's Great Barrier Reef is rapidly disappearing due to a host of factors -- all of which are influenced by humans, according to a new study. The report, published in the Proceedings of the National Academy of Sciences, tracks coral cover over the last 27 years and finds levels have fallen by nearly 50%.
The Great Barrier Reef is one of the world's most beloved natural attractions because of its remarkable array of sea life. But, according to researchers, a trio of factors has conspired to degrade the reef: tropical cyclones, attacks from the coral predator the crown-of-thorns starfish, and rising water temperatures. As a result, coral cover in the area has dropped from 28% in 1985 to 13% today, according to the team, which carried out the largest-ever continuous survey of reef condition for the study.
The study reveals how human impact on the natural environment can occur even when significant efforts are being made to protect a region, as they are in the Great Barrier Reef. Scientists believe the incidence of cyclones and the rising water temperatures are related to man-caused global warming. And researchers have even linked the rising numbers of predatory starfish to increases in the nutrient content of the water that flows from rivers into the ocean due to more intensive farming efforts and urban runoff.