More than 20,000 sq km of coast has succumbed to Australia’s first ever bloom of toxic Karenia cristata algae – and scientists worry it could explode again Get our breaking news email , free app or daily news podcast The largest and most destructive algal bloom in Australia’s history is persisting along parts of the South Australian coastline, a year on from when it was first detected. From a distance, it can be hard to grasp just how unusual and devastating the crisis has been. Most harmful