EDMONDS – The city is being slimed.
An effort is under way to kill a non-native, spongelike animal known as a sea squirt that was recently discovered in the Edmonds Underwater Dive Park.
“It’s kind of a pale orange, slimy growth,” said Doug Williams, a spokesman for the state Department of Fish and Wildlife.
The sea squirt, a variety of colonial tunicate native to Europe, occupies two areas in the dive park, officials said. One is about 30 square feet and the other about the size of a carpet sample, Williams said. The sea squirt overgrows other organisms and is considered a threat to native shellfish.
This is the first discovery of the species in Washington state, said Pam Meacham, assistant aquatic nuisance species coordinator for the Fish and Wildlife Department. It likely arrived in the ballast water of a ship, she said.
When the species was identified two weeks ago, both patches were covered with tarps to contain them, Meacham said.
“Every little piece of this that gets broken off is going to form a new colony,” she said.
On Saturday, five volunteer divers placed chlorine tablets around the growth and re-covered it with the tarp, said diver Bruce Higgins, the unofficial caretaker of the dive park. The tarp was pinned down to confine the chlorine to the organism.
The chlorine technique was used successfully on an invasive plant in California, but it’s not known if it will work on the sea squirt, Meacham said.
“We couldn’t find any historical reference of treatments on this thing,” she said. “What we’re doing is highly experimental right now. It was an immediate, rapid response to contain it and, if at all possible, kill it.”
The organism was discovered in April by Kinsey Frick, of Shoreline, a diver and fish biologist with the National Oceanic and Atmospheric Administration in Seattle.
Frick had seen the same type of sea squirt while diving in the Gulf of Maine.
“I thought, that looks familiar,” Frick said. These types of things “can go unnoticed, because not everyone knows what they see.”
Other tunicates found locally are native and do not pose a threat.
“They have natural regulators because they belong here,” Frick said. Non-native species “succeed because they are freed from predators and competitive restraints.”
Permits were required to take a sample of the organism from the dive park, which is a protected area. It took several months to get the permits to take the sample and apply the chlorine. The Fish and Wildlife Department is talking with the state Department of Ecology about getting a permit to treat the smaller patch, Meacham said.
The organism covered only a few square feet when discovered in April, she said. “It grew tremendously.”
Divers will check the organism once a week to monitor the treatment and test the water for chlorine levels, Meacham said. The state also will test the treatment and other measures in a lab to see how they work. Divers, tribes and others will be alerted to be on the lookout for the organism in case it migrates to other areas.
“We want to establish a method and a protocol for dealing with this species,” she said. “There’s a number of things we need to do to follow up.”
Reporter Bill Sheets: 425-339-3439 or sheets@heraldnet.com.
Sea squirts
Didemnum lahillei, the official name of the organism found recently off Edmonds, grows in two ways. It forms ropy, beardlike colonies that hang from hard surfaces, or grows in dense mats that encrust rocky seabeds, according to a U.S. Geological Survey Web site. It also has been found in San Francisco Bay, New England and New Zealand, in addition to its native North Sea, officials said.
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