Coral Autopsy Reveals Great Barrier Reef Collapse
Nutrient-rich slurry from farms has been causing coral populations on Australia’s Great Barrier Reef to crash for 90 years.
The corals collapsed between the 1920s and 1950s, say John Pandolfi at the University of Queensland in Brisbane and his colleagues. The team took cores from three reefs and worked out when the corals died. Two had little coral left after the 1950s, while the third had been colonised since then by different types.
By the 1920s, European settlers were farming intensively near rivers flowing onto the reef, boosting agricultural run-off by up to a factor of 20. Events like cyclones kill coral, but the extra nutrients in the water help seaweed move in afterwards, preventing coral from regenerating, says Terry Done of the Australian Institute of Marine Science in Townsville, Queensland.
The reefs were already in decline again when monitoring began in the 1980s, says Joana Figueiredo of James Cook University, also in Townsville. Pandolfi’s work shows that it was pristine until the 1920s.
Journal reference: Proceedings of the Royal Society B, DOI: 10.1098/rspb.2012.2100