“Two years ago, we manually removed all the algae from a reef, and in five or six months it was back to baseline conditions,” said State aquatic biologist Tony Montgomery.
This past year, biologists tried a new experiment, clearing a 3,000-square-meter (about a half-acre) patch reef in Kāne‘ohe Bay. They left one half of the reef alone, while on the other half they placed 1,200 native sea urchins.
The experiment was a stunning success.
“The portion of patch reef without urchins grew back in five to six months, with 35 percent alien algae cover, while the urchin side has been kept to 3 percent cover for the past 12 months,” Montgomery said.
“What this shows is that you can use the Super Sucker to reduce the density of alien algae, and then use the urchins to keep it down,” said Kim Hum, the Conservancy’s Hawai‘i director of marine programs.