for National Geographic News
In the battle against an exotic seaweed, biologists are employing a rather unusual solution: underwater vacuum cleaners.
Since 2006 the original Super Sucker, a barge-mounted device, has been operating in Kaneohe Bay, on the island of Oahu, where the seaweed invasion is particularly severe. (See a Hawaii map.)
At a recent scientific conference in Japan, biologists announced the arrival of "Super Sucker Junior," a smaller and more versatile unit that can operate in shallower waters and be easily transported between islands.
On land, non-native plant species sometimes outcompete native vegetation and take over habitat. The same phenomenon can happen in the sea. (Related: "It's Invaders vs. Invaders as Scientists Target Alien Species" [February 22, 2006].)
In Hawaii and elsewhere, scientists have noticed high-diversity coral communities shift to algae-dominated reefs with greatly reduced species diversity.
The problem posed by gorilla ogo and other invasive algae in Hawaii has been growing in magnitude for a number of years, experts say, and now has become dire.
"The algae invasion poses the largest current threat to the health of reefs in Hawaii," said Cynthia Hunter, a marine biologist at the University of Hawaii.
Thick coatings of algae can kill corals by blocking them from sunlight and flows of fresh seawater.
Some species have been particularly affected, Hunter said, including a species of rice coral that is now rapidly disappearing.
Algae also fill in the cracks and crevices that make coral reefs a safe haven for fish and other forms of marine life. Even larger animals such as sea turtles may be excluded from their normal resting areas.
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