seaweed may be killing
Kaneohe Bay coral
A researcher broughtBy Lori Tighe
the suspect seaweed from
A beefy alien seaweed appears to be killing coral in Kaneohe Bay, and researchers want to find out why.
The seaweed, Kappaphycus alvarezii, nicknamed "brown licorice," is thicker, taller, bushier and bumpier than the local ogo seaweed.
"The seaweed is growing all over the coral and perhaps smothering it. We don't know why," said Dave Eckert, aquatic biologist with the Department of Land and Natural Resources. "We want to find out more. We don't want to push the panic button yet and say this is the monster that ate Cleveland."
Scientists have spotted dead coral underneath the thick canopy of this seaweed, but they don't know if the coral died before the seaweed began growing on it, Eckert said.
The seaweed, a native of the Philippines, doesn't attack the coral there. But Hawaiian corals may not have similar defenses, Eckert said.
Hawaiian corals grow much more slowly than in warmer climates because the waters here are the coldest corals can tolerate, Eckert explained.
"Our fastest-growing coral grows just one centimeter each year," he said.
If the alien seaweed is choking Hawaii's corals, it will devastate the ecosystem, Eckert said. The coral reefs provide the home for a plethora of plants, fish and microorganisms.
"It's alarming enough that we're supporting research money, about $10,000, to find out about this seaweed," Eckert said.
A researcher brought the seaweed from the Philippines to Kaneohe in the mid-1970s, Eckert said. The researcher became interested in farming it for its natural gel, called carrageen, a smoothening agent used in ice cream, toothpaste, jellies, medicines and paint. But the labor cost involved to farm the seaweed made it an unworthy venture, Eckert said.
The seaweed somehow escaped into the bay.
It grew, then died down, then apparently picked up again recently, Eckert said.
A DLNR team discovered the seaweed growing rampantly again, he said.
Monica Woo, a marine biologist graduate student with University of Hawaii, will work as the lead researcher investigating the seaweed. She recently put out 60 small cages around the bay with the alien seaweed inside. Woo wants to find out if the seaweed has any natural predators that may keep it in check.
"The main thing that concerns us about it is it can grow in thick mats, preventing light from reaching the coral to grow," Woo said. "With the cages, we want to determine how quickly the seaweed is growing and what is feeding on it."
Researchers found the seaweed most densely growing on the bay's back reef, between the outer barrier reef and the sand bar, and as far up as Kualoa. Unconfirmed reports indicate the seaweed has reached Waimanalo, Eckert said.
"The seaweed likes rough, turbulent water with a lot of action," Eckert said.
The project should wrap up next April, and DLNR will inform the public about findings.