Researchers studying events last year in the sea off Australia's west coast, where sea temperatures were 3 degrees to 7 degrees Fahrenheit warmer than usual along a 1,200-mile stretch of coast, say that impact can be extreme and rapid.
When Daniel Smale at the University of Western Australia in Perth and colleagues surveyed the area in November 2011, as they have done every year since 2006, they found the formerly pristine and stable ecosystem had completely changed, NewScientist.com reported.
The ecosystem had lost complexity, Smale said, as the kelp that covered 80 percent of the area, providing a range of habitats, had declined to cover just 50 percent.
Mats of algal "turf," which provide fewer distinct habitat niches, had moved in instead, he said.
"In less than a year, we can have ecological switches from one kind of habitat to another," Smale said.
Smale said he would return to the area in November to see whether the changes are permanent and said he suspects some will be.