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Reef villain meets rival: the Super Sucker

Hawaii's solution to choking seaweed is a huge but gentle vacuum. The lowly urchin will take care of stragglers.

December 28, 2007|Kenneth R. Weiss | Times Staff Writer

COCONUT ISLAND, HAWAII — What was intended as a noble science experiment in the 1970s has turned into a modern-day plague for the delicate coral reefs surrounding the University of Hawaii's research station here.

A professor scoured the seas for the heartiest, fastest-growing algae to help Third World nations develop a seaweed crop for carrageenan -- the gelatinous thickener and emulsifier used in such items as toothpaste, shoe polish and nonfat ice cream.

The late Maxwell Doty succeeded, in one regard. His research helped the Philippines and other island nations establish multimillion-dollar industries to supply carrageenan to the food, beverage and cosmetic industries.

Yet his efforts also left an unwanted legacy. Open-cage experiments inoculated Hawaiian coastal waters with half a dozen types of foreign algae. These aggressive invaders have smothered at least half the reefs in Kaneohe Bay on Oahu's west coast and have begun to spread to waters beyond.

For The Record
Los Angeles Times Saturday, December 29, 2007 Home Edition Main News Part A Page 2 National Desk 1 inches; 27 words Type of Material: Correction
Reef relief: An article in Friday's Section A on invasive algae said Oahu's Kaneohe Bay is on its west coast. It's on the Hawaiian island's east coast.

The sprouting problem has kept professors, graduate students and state officials busy trying to rein in the shaggy mats of thick-stemmed seaweed, which threaten coral reefs and the fish, turtles and other sea life that depend on them. After years of trial and error, scientists believe they have arrived at a solution.

It involves a giant underwater vacuum that they call the Super Sucker.

On a recent Sunday, a pair of divers ripped chunks of the foot-thick blanket of algae from atop a coral reef and fed it into a fat hose.

The suction is created by back-pressure from a special vacuum pump that doesn't damage any animals inadvertently scooped up -- and it doesn't chop the algae into bits, which could make the effort futile: Even the smallest seaweed fragments flushed back into the water reseed the reef with the aggressive algae.

On a barge above the divers, biology professor Cynthia Hunter sifted through the piles atop tight-mesh screens to remove any animals accidentally vacuumed up. She then bagged the seaweed to be taken ashore for composting and use as fertilizer in agricultural fields.

"It's pretty clean work," said Hunter. She showed that only a few bits of coral ended up in the glistening mix of golden-green seaweed.

Yet it's also a slow and tedious task, even though the Super Sucker can scoop up about 800 pounds of algae an hour.

No one knows that better than Eric Conklin, a newly minted doctor of zoology who has spent hours and hours feeding clumps of "gorilla ogo" and "smothering seaweed" and other invasive algae into the Super Sucker.

"If all we were doing is vacuuming the reef, it would come back and we'd be back at it again," Conklin said. "Our plan is to knock back the growth so it won't spread and [to] give our long-term solutions a chance to take hold."

The hopes of long-term solution rest largely on the lowly sea urchin, a softball-size creature with spines that eats invasive algae.

One of the problems is that the populations of urchins around Hawaii have plunged because of excessive harvesting. They are collected for their gonads, which are prized as uni by sushi-bar patrons.

At the lab on Coconut Island, university researchers are learning how to propagate one species, the collector urchin, so they can scatter baby urchins on freshly vacuumed reefs.

"The urchins can do the much harder, tedious work of grazing the little bits of algae -- the work we couldn't do even paying minimum wage," said Celia Smith, a botany professor.

The strategy has worked in small test plots, where thumb-size nubs of corals have rebounded. Now the university, working with the Nature Conservancy and Hawaii's Department of Land and Natural Resources, is scaling up the program to attack the invaders a reef at a time.

Invasive seaweed is hardly unique to Hawaii. Vast areas of the Mediterranean seafloor have become swaying fields of a killer algae called Caulerpa taxifolia, which was mistakenly released into waters by the Oceanographic Museum of Monaco. The fernlike Caulerpa was popular in saltwater aquariums because it's easy to grow.

When an outbreak of Caulerpa was discovered in the harbor at Huntington Beach, marine biologists rushed to cover the area with plastic tarps and to poison the invader -- along with everything else -- with chlorine.

Researchers here at the University of Hawaii have sought a gentler approach, given what lies beneath the interwoven mats of smothering algae and gorilla ogo (which go by the scientific names Eucheuma denticulatum and Gracilaria salicornia). Coral reefs around the world are struggling from a combination of assaults besides the extra-warm water that causes coral bleaching.

Decades of overfishing have removed animals that keep algae growth in check. And excessive plant food -- nitrogen and phosphorus compounds -- is spilling onto reefs from agricultural runoff and sewer pipes.

The resulting algal overgrowth shades coral reefs -- colonies of tiny animals, which need sunlight to survive -- as well as promotes the spread of harmful bacteria and various infections.

Smith, the botanist, calls it "one of life's rich ironies" that she has spent so much of her career trying to protect corals from something unleashed by Doty -- her former professor.

Smith was hired in 1988 to succeed him as the university's algae specialist.

"One thing I've learned about these reefs: They are really balanced on a knife's edge," Smith said. "You can push them so far and then you lose them. We are perilously close."

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ken.weiss@latimes.com

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