"Humans have wrecked reefs in 30 years"

Humans have caused more damage in the past 30 years than the reefs have experienced at any time in the last 220,000 years, say Jeremy Jackson and John Pandolfi according to a report in New Scientist of their paper in Ecology Letters, vol 9, p 818

The fossil record shows that reefs near Barbados had been dominated by a large branching species called Elkhorn coral as recently as a century ago, and until then had survived intact through hurricanes, climate change and geological movement. Yet now they are overwhelmed by algae and seaweed.