Invasion of the snowflake coral

Workers try to smother the pest around Kauai

For more than a year, conservation workers have been quietly battling one of Hawaii's most serious aquatic invasive species -- snowflake coral -- under the only commercial pier in Kauai's Port Allen.

The battle is being waged with plastic stretch-wrap -- the kind shippers use to bind products to pallets.

Scuba divers enter the murky, 30-foot-deep water under the pier and tightly wrap the columns that support it with stretch-wrap. They bind it with a saltwater-resistant tape. And they leave.

Their objective is to kill the soft coral by smothering it, said Tony Montgomery, an aquatic biologist with the state Department of Land and Natural Resources. The plastic "cuts off water flow, cuts off oxygen and nutrients and destroys it," he said.

Perhaps it's a fitting method, since smothering is also how the snowflake coral is killing precious black coral beds between Maui and Lanai. Those stands of black coral "trees" are the state's largest and the only ones that are commercially harvested.

The snowflake coral (Carijoa riisei) is doing so much damage in Maui County that fishery managers plan to reduce black coral harvesting until the snowflake coral can be stopped. If it can.

Sam Kahng, who wrote his Ph.D. dissertation on the snowflake coral, calls it "the most invasive of an estimated 287 marine invertebrates in Hawaii."

The DLNR Division of Aquatic Resources hopes to eradicate snowflake coral in Kauai's waters because they hold the second-largest black coral bed in the state, Montgomery said.

Eradication is a lofty goal, especially of an organism that can reproduce both sexually and asexually, from fragments, Montgomery said.

One of the things Kauai has going for it is its distance from the nearest major island of Oahu. If the snowflake coral can be knocked out, maybe it can be kept out, said Dan Polhemus, administrator of the Division of Aquatic Resources.

The first of the Port Allen pier's 738 columns that had snowflake coral on them were wrapped more than a year ago, Montgomery said. The last were wrapped in May.

The job would have gone quicker if there had been more people available to do it more consistently, Montgomery said.

Four to five Division of Aquatic Resources staff members go to Kauai every month to battle the coral, he said. Sometimes they have had help from others -- the Kauai Invasive Species Committee, University of Hawaii divers, scientists from the National Oceanic and Atmospheric Administration. Sometimes they haven't.

Since May, the scientists have returned monthly to look for any new colonies of the fast-growing coral, Montgomery said.

And before they unwrap any of the dead coral under the plastic, the team wants to see nothing new sprouting. So far, that hasn't happened yet, he said, but maybe it will soon.

"We've been finding 10 to 15 colonies every month," Montgomery said. "But the last trip, they were very small colonies. You could count the number of polyps."

Other creatures such as sea squirts and sponges have been killed by the wrapping, Montgomery acknowledged. "But the port is a disturbed habitat. Most of other organisms on there also are alien species," he said.

When no more new colonies are seen, the wraps can come off and the team will refocus on eliminating Kauai's other snowflake coral infestation -- at a popular diving spot at Makawena Point.

Since plastic wrap won't work in the open ocean, other methods will have to be devised, Montgomery said. One possibility is a hot water gun, he said.

Montgomery estimates that more than $100,000 in grant money has been spent on travel and supplies for the project. He hasn't yet calculated the value of staff or volunteer time.